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Device and method for determining black point    
United States Patent6122002   
Link to this pagehttp://www.wikipatents.com/6122002.html
Inventor(s)Ohara; Kiyotaka (Nagoya, JP), Hibino; Masaaki (Yokkaichi, JP), Kobayakawa; Koji (Ichinomiya, JP), Ueda; Masashi (Nagoya, JP), Hori; Masaaki (Tajimi, JP), Yoshida; Yasunari (Aichi-ken, JP)
AbstractThe standard brightness region is displayed with input values of zero. The comparison brightness region is displayed with an input value which is variable in the range of 0 to 255. The standard brightness and comparison brightness regions are displayed next to each other in the display. The input value is changed from zero. A first black point is determined as an input value which causes the comparison brightness region to first appear distinguishable from the black regions of the standard brightness regions. Then, the input value is changed from 255. A second black point is determined as an input value which causes the comparison brightness region to first appear indistinguishable from the black regions of the standard brightness regions. Then, a black point is calculated as an average of the first and second black points.
   














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Drawing from US Patent 6122002
Device and method for determining black point - US Patent 6122002 Drawing
Device and method for determining black point
Inventor     Ohara; Kiyotaka (Nagoya, JP) , Hibino; Masaaki (Yokkaichi, JP) , Kobayakawa; Koji (Ichinomiya, JP) , Ueda; Masashi (Nagoya, JP) , Hori; Masaaki (Tajimi, JP) , Yoshida; Yasunari (Aichi-ken, JP)
Owner/Assignee     Brother Kogyo Kabushiki Kaisha (Nagoya, JP)
Patent assignment
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Publication Date     September 19, 2000
Application Number     08/856,390
PAIR File History     Application Data   Transaction History
Image File Wrapper   Patent Term   Fees
Litigation
Filing Date     May 14, 1997
US Classification     348/191 345/690 348/189 348/687 348/689 348/E17.004 348/E17.005
Int'l Classification    
Examiner     Peng; John K.
Assistant Examiner     Natnael; Paulos
Attorney/Law Firm     Oliff & Berridge, PLC
Address
Parent Case    
Priority Data     May 16, 1996 [JP] 8-121836
USPTO Field of Search     358/447 358/515 358/529 358/531 358/532 348/687 348/691 348/379 348/189 348/180 348/184 348/191 348/695 348/689 348/243 345/147
Patent Tags     determining black point
   
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5754222
Daly et al.

May,1998

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5570108
McLaughline et al.

Oct,1996

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5483259
Sachs

Jan,1996

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5381349
Winter et al.

Jan,1995

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5298993
Edgar et al.

Mar,1994

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Hung et al.

Sep,1990

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What is claimed is:

1. A method for determining a black point of a display, the method comprising the steps of:

controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point;

controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the standard brightness region;

gradually changing the value inputted for the comparison brightness region so that the comparison brightness region exhibits a brightness change both in a direction from a first state distinguishable from the standard brightness region into a second state indistinguishable from the standard brightness region and in a reverse direction from the second state into the first state, wherein the value changing step includes the steps of:

gradually increasing the value inputted for the comparison brightness region from a value lower than the black point;

determining, as a first black point, the value inputted when the comparison brightness region first becomes distinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually increased;

gradually decreasing the value inputted for the comparison brightness region from a value higher than the black point; and

determining, as a second black point, the value inputted when the comparison brightness region first becomes indistinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually decreased; and

determining the black point of the display based on both the first and second black points.

2. A method as claimed in claim 1,

wherein the predetermined value is lower than the black point of the display, and

wherein a user is allowed to gradually increase the value inputted for the comparison brightness region from the predetermined value until the comparison brightness region first becomes distinguishable from the standard brightness region, and wherein the user is allowed to gradually decrease the value inputted for the comparison brightness region from another predetermined value higher than the black point until the comparison brightness region first becomes indistinguishable from the standard brightness region.

3. A method as claimed in claim 2, wherein the user is allowed to input a first black point determination instruction when the user visually confirms that the comparison brightness region first becomes distinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually increased, the first black point being determined in response to the first black point determination instruction, and wherein the user is allowed to input a second black point determination instruction when the user visually confirms that the comparison brightness region first becomes indistinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually decreased, the second black point being determined in response to the second black point determination instruction.

4. A method as claimed in claim 3, wherein the predetermined value is equal to a possible minimum value inputtable to the display, and the other predetermined value is equal to a possible maximum value inputtable to the display, and wherein the user is allowed to gradually change the value inputted for the comparison brightness region from the predetermined value until inputting the first black point determination instruction, and wherein the user is allowed to gradually change the value inputted for the comparison brightness region from the other predetermined value until inputting the second black point determination instruction.

5. A method as claimed in claim 1, wherein the black point of the display is calculated to have a value equal to an average of the first and second black points.

6. A method for determining a black point of a display, the method comprising the steps of:

controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point, the predetermined value being lower than the black point of the display;

controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the standard brightness region, wherein the comparison brightness region display controlling step includes the steps of:

setting an input value for each pixel in the comparison brightness region so that the input value gradually decreases from a first input value which is higher than the black point to the predetermined value in a direction toward the standard brightness region; and

controlling the display to display the comparison brightness region with the set input value so that brightness of the comparison brightness region gradually decreases in a direction toward the standard brightness region so as to define therein a portion appearing distinguishable from the standard brightness region and a remaining portion appearing indistinguishable from the standard brightness region;

gradually changing the value inputted for the comparison brightness region, the input value changing step including the step of changing the input value for each pixel in the comparison brightness region while maintaining the gradual decreasing tendency until a parameter indicative of the distinguishable portion satisfies a predetermined condition; and

determining the black point of the display based on the condition-satisfying input value for a pixel that is located on the border line between the distinguishable portion and the indistinguishable portion.

7. A method as claimed in claim 6, wherein the parameter indicative of the distinguishable portion includes either one of a width, a height, and an area of the distinguishable portion.

8. A method as claimed in claim 6, wherein the parameter indicative of the distinguishable portion includes a width of the distinguishable portion.

9. A method as claimed in claim 6, wherein the gradual decreasing tendency is defined as a predetermined function based on an input value for a highest brightness pixel in the comparison brightness region and based on a distance between each pixel and the highest brightness exhibiting pixel, wherein the input value changing step changes the input value for the highest brightness exhibiting pixel, thereby allowing the parameter of the distinguishable portion to vary, and wherein the input value for the pixel on the border is determined dependently on the input value for the highest brightness exhibiting pixel, the predetermined condition, and the predetermined function.

10. A method for determining a black point of a display, the method comprising the steps of:

controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point, the predetermined value being higher than the black point of the display;

controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the standard brightness region, wherein the comparison brightness region display controlling step includes the steps of:

setting an input value for each pixel in the comparison brightness region so that the input value gradually increases from a first input value which is lower than the black point to the predetermined value in a direction toward the standard brightness region; and

controlling the display to display the comparison brightness region with the set input value so that brightness of the comparison brightness region gradually increases in a direction toward the standard brightness region so as to define therein a portion appearing distinguishable from the standard brightness region and a remaining portion appearing indistinguishable from the standard brightness region;

gradually changing the value inputted for the comparison brightness region, the input value changing step including the step of changing the input value for each pixel in the comparison brightness region while maintaining the gradual increasing tendency until a parameter indicative of the distinguishable portion satisfies a predetermined condition; and

determining the black point of the display based on the condition-satisfying input value for a pixel that is located on the border line between the distinguishable portion and the indistinguishable portion.

11. A method as claimed in claim 10, wherein the parameter indicative of the distinguishable portion includes either one of a width, a height, and an area of the distinguishable portion.

12. A method as claimed in claim 10, wherein the parameter indicative of the distinguishable portion includes a width of the distinguishable portion.

13. A method as claimed in claim 10, wherein the gradual increasing tendency is defined as a predetermined function based on an input value for a lowest brightness pixel in the comparison brightness region and based on a distance between each pixel and the lowest brightness exhibiting pixel, wherein the input value changing step changes the input value for the lowest brightness exhibiting pixel, thereby allowing the

parameter of the distinguishable portion to vary, and wherein the input value for the pixel on the border is determined dependently on the input value for the lowest brightness exhibiting pixel, the predetermined condition, and the predetermined function.

14. A device for determining a black point of a display, the device comprising:

means for controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point;

means for controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the standard brightness region;

means for gradually changing the value inputted for the comparison brightness region so that the comparison brightness region exhibits a brightness change both in a direction from a first state distinguishable from the standard brightness region into a second state indistinguishable from the standard brightness region and in a reverse direction from the second state into the first state, wherein the value changing means includes:

means for gradually increasing the value inputted for the comparison brightness region from a value lower than the black point;

means for determining, as a first black point, the value inputted when the comparison brightness region first becomes distinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually increased;

means for gradually decreasing the value inputted for the comparison brightness region from a value higher than the black point; and

means for determining, as a second black point, the value inputted when the comparison brightness region first becomes indistinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually decreased; and

means for determining the black point of the display based on both the first and second black points.

15. A device as claimed in claim 14,

wherein the predetermined value is lower than the black point of the display, and

further comprising input means for enabling a user to gradually increase the value inputted for the comparison brightness region from the predetermined value until the comparison brightness region first becomes distinguishable from the standard brightness region, and wherein the input means further enables the user to gradually decrease the value inputted for the comparison brightness region from another predetermined value higher than the black point until the comparison brightness region first becomes indistinguishable from the standard brightness region.

16. A device as claimed in claim 15, wherein the input means further enables the user to input a first black point determination instruction when the user visually confirms that the comparison brightness region first becomes distinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually increased, the first black point determining means determining the first black point in response to the first black point determination instruction, the input means further enables the user to input a second black point determination instruction when the user visually confirms that the comparison brightness region first becomes indistinguishable from the standard brightness region while the value inputted for the comparison brightness region is being gradually decreased, the second black point determination means determining the second black point in response to the second black point determination instruction.

17. A device as claimed in claim 16, wherein the predetermined value is equal to a possible minimum value inputtable to the display, and the other predetermined value is equal to a possible maximum value inputtable to the display, and wherein the input means enables the user to gradually change the value inputted for the comparison brightness region from the predetermined value until inputting the first black point determination instruction, and wherein the input means allows the user to gradually change the value inputted for the comparison brightness region from the other predetermined value until inputting the second black point determination instruction.

18. A device as claimed in claim 14, wherein the black point of the display is calculated to have a value equal to an average of the first and second black points.

19. A device for determining a black point of a display, the device comprising:

means for controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point;

means for controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the standard brightness region, wherein the comparison brightness region display controlling means includes:

means for setting an input value for each pixel in the comparison brightness region so that the input value gradually decreases from a first input value which is higher than the black point to the predetermined value in a direction toward the standard brightness region; and means for controlling the display to display the comparison brightness region with the set input value so that brightness of the comparison brightness region gradually decreases in a direction toward the standard brightness region so as to define therein a portion appearing distinguishable from the standard brightness region and a remaining portion appearing indistinguishable from the standard brightness region;

means for gradually changing the value inputted for the comparison brightness region, the input value changing means including means for changing the input value for each pixel in the comparison brightness region while maintaining the gradual decreasing tendency until a parameter indicative of the distinguishable portion satisfies a predetermined condition; and

means for determining the black point of the display based on the condition-satisfying input value for a pixel that is located on the border line between the distinguishable portion and the indistinguishable portion.

20. A device as claimed in claim 19, wherein the parameter indicative of the distinguishable portion includes either one of a width, a height, and an area of the distinguishable portion.

21. A device as claimed in claim 19, wherein the parameter indicative of the distinguishable portion includes a width of the distinguishable portion.

22. A device as claimed in claim 19, wherein the gradual decreasing tendency is defined as a predetermined function based on an input value for a highest brightness pixel in the comparison brightness region and based on a distance between each pixel and the highest brightness exhibiting pixel, wherein the input value changing means changes the input value for the highest brightness exhibiting pixel, thereby allowing the parameter of the distinguishable portion to vary, and wherein the input value for the pixel on the border is determined dependently on the input value for the highest brightness exhibiting pixel, the predetermined condition, and the predetermined function.

23. A device for determining a black point of a display, the device comprising:

means for controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point, the predetermined value being higher than the black point of the display;

means for controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the standard brightness region, wherein the comparison brightness region display controlling means includes:

means for setting an input value for each pixel in the comparison brightness region so that the input value gradually increases from a first input value which is lower than the black point to the predetermined value in a direction toward the standard brightness region; and

means for controlling the display to display the comparison brightness region with the set input value so that brightness of the comparison brightness region gradually increases in a direction toward the standard brightness region so as to define therein a portion appearing distinguishable from the standard brightness region and a remaining portion appearing indistinguishable form the standard brightness region;

means for gradually changing the value inputted for the comparison brightness region, the input value changing means including means for changing the input value for each pixel in the comparison brightness region while maintaining the gradual increasing tendency until a parameter indicative of the distinguishable portion satisfies a predetermined condition; and

means for determining the black point of the display based on the condition-satisfying input value for a pixel that is located on the border line between the distinguishable portion and the indistinguishable portion.

24. A device as claimed in claim 23, wherein the parameter indicative of the distinguishable portion includes either one of a width, a height, and an area of the distinguishable portion.

25. A device as claimed in claim 23, wherein the parameter indicative of the distinguishable portion includes a width of the distinguishable portion.

26. A device as claimed in claim 23, wherein the gradual increasing tendency is defined as a predetermined function based on an input value for a lowest brightness pixel in the comparison brightness region and based on a distance between each pixel and the lowest brightness exhibiting pixel, wherein the input value changing means changes the input value for the lowest brightness exhibiting pixel, thereby allowing the parameter of the distinguishable portion to vary, and wherein the input value for the pixel on the border is determined dependently on the input value for the lowest brightness exhibiting pixel, the predetermined condition, and the predetermined function.

27. A device for determining a black point of a display, the device comprising:

means capable of driving a display to produce a standard brightness region on a display screen based on a predetermined input value, the predetermined input value being lower than the black point, the standard brightness region exhibiting a predetermined brightness corresponding to the predetermined input value, the standard brightness region serving as a standard for determining a black point of the display, the driving means being further capable of driving the display to produce a comparison brightness region on the display screen based on a comparison input value, the comparison brightness region exhibiting a brightness corresponding to the comparison input value and being located next to the standard brightness region;

control means for increasing the comparison input value from a value lower than the black point and for decreasing the comparison input value from another predetermined value higher than the black point while controlling the driving means to drive the display to display the standard brightness region and the comparison brightness region;

input means for enabling a user to input a black point determination instruction when the comparison brightness region first appears distinguishable from the standard brightness region while the comparison input value is being increased and for enabling a user to input a black point determination instruction also when the comparison brightness region first appears indistinguishable from the standard brightness region while the comparison input value is being decreased; and

black point calculation means for calculating a black point of the display based on both a comparison input value inputted when the black point determination instruction is inputted while the comparison input value is being increased and another comparison input value inputted when the black point determination instruction is inputted while the input value is being decreased.

28. A device for determining a black point of a display, the device comprising:

standard brightness region generating means for determining a value, to be inputted for a standard brightness region, which is smaller than a black point of a display and for controlling the display to display the standard brightness region with the determined input value, the standard brightness region exhibiting a corresponding brightness, the standard brightness region serving as a standard for determining a black point;

comparison brightness region generating means for setting an input value for each pixel in a comparison brightness region so that the input value varies from a first input value higher than the black point to a second input value lower than the black point in a predetermined gradual decreasing tendency so that the input value for the comparative brightness region gradually decreases from the first input value to the second input value in a direction toward the standard brightness region and for controlling the display to display the comparison brightness region with the set input values so that brightness of the comparison brightness region gradually decreases in a direction toward the standard brightness region, the comparison brightness region being located next to the standard brightness region;

predetermined condition setting means for setting a predetermined condition to be compared with a parameter of a portion in the comparison brightness region that appears distinguishable from the standard brightness region;

input value changing means for changing the input value for each pixel in the comparison brightness region while maintaining the gradual decreasing tendency;

black point determination instruction input means for enabling a user to input a black point determination instruction when the parameter of the portion, in the comparison brightness region, that appears distinguishable from the standard brightness region satisfies the predetermined condition; and

black point calculation means for calculating a black point of the display based on the input value set for a pixel located on a border line between the condition-satisfying distinguishable portion and a remaining indistinguishable portion when the black point determination instruction is inputted.

29. A device of claim 28, wherein the comparison brightness region generating means sets the gradual decreasing tendency as a predetermined function based on an input value for a highest brightness pixel in the comparison brightness region and based on a distance between each pixel and the highest brightness exhibiting pixel, wherein the parameter of the distinguishable portion varies as the input value changing means changes the input value for the highest brightness pixel, and wherein the black point calculation means determines the input value for the pixel on the border dependently on the input value for the highest brightness exhibiting pixel, the predetermined condition, and the predetermined function.

30. A device as claimed in claim 29, wherein the input value changing means allows the user to change an input value for the highest brightness exhibiting pixel until the user inputs the black point determination instruction.

31. A device as claimed in claim 29, wherein the predetermined function is defined to gradually decrease the input value for the comparison brightness region from the highest brightness pixel which is located most distant from the standard brightness region toward a lowest brightness exhibiting pixel which is located next to the standard brightness region, the predetermined function continuously connects the brightness of the lowest brightness exhibiting pixel to the brightness of the standard brightness region.

32. A device for determining a black point of a displays the device comprising:

standard brightness region generating means for determining a value, to be inputted for a standard brightness region, which is higher than a black point of a display and for controlling the display to display the standard brightness region with the determined input value, the standard brightness region exhibiting a corresponding brightness, the standard brightness region serving as a standard for determining a black point;

comparison brightness region generating means for setting an input value for each pixel in a comparison brightness region so that the input value varies from a third input value lower than the black point to a fourth input value higher than the black point in a predetermined gradual increasing tendency so that the input value for the comparison brightness region gradually increases from the third input value to the fourth input value in a direction toward the standard brightness region and for controlling the display to display the comparison brightness region with the set input values so that brightness of the comparison brightness region gradually increases in a direction toward the standard brightness region, the comparison brightness region being located next to the standard brightness region;

predetermined condition setting means for setting a predetermined condition to be compared with a parameter of a portion in the comparison brightness region that appears distinguishable from the standard brightness region;

input value changing means for changing the input value for each pixel in the comparison brightness region while maintaining the gradual increasing tendency;

black point determination instruction input means for enabling a user to input a black point determination instruction when the parameter of the portion, in the comparison brightness region, that appears distinguishable from the standard brightness region satisfies the predetermined condition; and

black point calculation means for calculating a black point of the display based on the input value set for a pixel located on a border line between the condition-satisfying distinguishable portion and a remaining indistinguishable portion when the black point determination instruction is inputted.

33. A device of claim 32, wherein the comparison brightness region generating means sets the gradual increasing tendency as a predetermined function based on an input value for a lowest brightness pixel in the comparison brightness region and based on a distance between each pixel and the lowest brightness exhibiting pixel, wherein the parameter of the distinguishable portion varies as the input value changing means changes the input value for the lowest brightness pixel, and wherein the black point calculation means determines the input value for the pixel on the border dependently on the input value for the lowest brightness exhibiting pixel, the predetermined condition, and the predetermined function.

34. A device as claimed in claim 33, wherein the input value changing means allows the user to change an input value for the lowest brightness exhibiting pixel until the user inputs the black point determination instruction.

35. A device as claimed in claim 33, wherein the predetermined function is defined to gradually increase the input value for the comparison brightness region from the lowest brightness pixel which is located most distant from the standard brightness region toward a highest brightness exhibiting pixel which is located next to the standard brightness region, the predetermined function continuously connects the brightness of the highest brightness exhibiting pixel to the brightness of the standard brightness region.
 Description Submit all comments and votes
 


BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for determining a black point of a display and a device for determining the black point.

2. Description of Related Art

Display characteristic of a display device depends on a relationship between a value of a signal inputted to the display device and brightness actually obtained on the display device.

The CRT display has a non-linear display characteristic between the value of a signal inputted to the display and brightness actually obtained on the display. More specifically, the display characteristic is as shown in FIG. 1, in which the value of relative brightness changes non-linearly as the value of the input signal varies. The relative brightness is defined as a value of brightness actually attained on the display relative to a maximum brightness which is normalized to a predetermined value of 255. As shown in the figure, the relative brightness decreases as the input value decreases, and reaches zero (0) when the input value reaches a certain value BP which is called as a "black point".

Assuming that each of the input value X and the relative brightness Yd changes among 256 levels 0 to 255, the display characteristic can be approximated by the following exponential function:

It is noted that the black point BP changes according to a user's control of brightness of the display. The black point BP also changes in time, and according to respective users' visual sensitivities to light. It is therefore necessary to know the black point BP of the display in order to correctly calibrate the display and in order to attain color matching between colors displayed on the display and colors printed by the printer.

In order to determine the black point BP, it is conceivable that the display be controlled to display a test pattern shown in FIG. 2. The test pattern includes a standard brightness region A sandwiched between a pair of identical comparison brightness regions B. The standard brightness region A is formed by an input value X of zero (X=0). The comparison brightness regions B are formed by an input value X which is variable in a range higher than zero (X>0). The user manipulates the device to change the input value X for the regions B until the comparison brightness regions B become lighter than and distinguishable from the region A. In more concrete terms, when the user perceives some slight difference in brightness between the regions A and B, he or she enters this into the device by, for example, pressing a key. The device sets, as the black

point BP, the value X which is presently inputted when the input from the user is received.

According to this conceivable method, however, an unskilled user may not determine the black point accurately within a short period of time. It is therefore desirable to provide an improved method for enabling the unskilled user to easily determine the black point.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to solve the above problems and to provide an improved method and device capable of easily determining the black point accurately within a short period of time and for enabling a user to easily determine the black point.

In order to attain the above and other objects, the present invention provides a method for determining a black point of a display, the method comprising the steps of: controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point; controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the first standard brightness region; gradually changing the value inputted for the comparison brightness region so that the comparison brightness region exhibits a brightness change both in a direction from a first state distinguishable from the standard brightness region into a second state indistinguishable from the standard brightness region and in a reverse direction from the second state into the first state; and determining the black point of the display based on the brightness change.

According to another aspect, the present invention provides a device for determining a black point of a display, the device comprising: means for controlling a display to display a standard brightness region with an inputted predetermined value which is different from a black point of the display, the standard brightness region exhibiting a predetermined brightness, the standard brightness region serving as a standard for determining a black point; means for controlling the display to display a comparison brightness region with a variably-inputted value, the comparison brightness region being located next to the first standard brightness region; means for gradually changing the value inputted for the comparison brightness region so that the comparison brightness region exhibits a brightness change both in a direction from a first state distinguishable from the standard brightness region into a second state indistinguishable from the standard brightness region and in a reverse direction from the second state into the first state; and means for determining the black point of the display based on the brightness change.

According to a further aspect, the present invention provides a device for determining a black point of a display, the device comprising: means capable of driving a display to produce a standard brightness region on a display screen based on a predetermined input value, the predetermined input value being lower than the black point, the standard brightness region exhibiting a predetermined brightness corresponding to the predetermined input value, the standard brightness region serving as a standard for determining a black point of the display, the driving means being further capable of driving the display to produce a comparison brightness region on the display screen based on a comparison input value, the comparison brightness region exhibiting a brightness corresponding to the comparison input value and being located next to the standard brightness region; control means for increasing the comparison input value from a value lower than the black point and for decreasing the comparison input value from another predetermined value higher than the black point while controlling the driving means to drive the display to display the standard brightness region and the comparison brightness region; input means for enabling a user to input a black point determination instruction when the comparison brightness region first appears distinguishable from the standard brightness region while the comparison input value is being increased and for enabling a user to input a black point determination instruction also when the comparison brightness region first appears indistinguishable from the standard brightness region while the comparison input value is being decreased; and black point calculation means for calculating a black point of the display based on both a comparison input value inputted when the black point determination instruction is inputted while the comparison input value is being increased and another comparison input value inputted when the black point determination instruction is inputted while the input value is being decreased.

According to still another aspect, the present invention provides a device for determining a black point of a display, the device comprising: standard brightness region generating means for determining a value, to be inputted for a standard brightness region, which is smaller than a black point of a display and for controlling the display to display the standard brightness region with the determined input value, the standard brightness region exhibiting a corresponding brightness, the standard brightness region serving as a standard for determining a black point; comparison brightness region generating means for setting an input value for each pixel in a comparison brightness region so that the input value varies from a first input value higher than the black point to a second input value lower than the black point in a predetermined gradual decreasing tendency so that the input value for the comparative brightness region gradually decreases from the first input value to the second input value in a direction toward the standard brightness region and for controlling the display to display the comparison brightness region with the set input values so that brightness of the comparison brightness region gradually decreases in a direction toward the standard brightness region, the comparison brightness region being located next to the standard brightness region; predetermined condition setting means for setting a predetermined condition to be compared with a parameter of a portion in the comparison brightness region that appears distinguishable from the standard brightness region; input value changing means for changing the input value for each pixel in the comparison brightness region while maintaining the gradual decreasing tendency; black point determination instruction input means for enabling a user to input a black point determination instruction when the parameter of the portion, in the comparison brightness region, that appears distinguishable from the standard brightness region satisfies the predetermined condition; and black point calculation means for calculating a black point of the display based on the input value set for a pixel located on a border line between the condition-satisfying distinguishable portion and a remaining indistinguishable portion when the black point determination instruction is inputted.

According to still another aspect, the present invention provides a device for determining a black point of a display, the device comprising: standard brightness region generating means for determining a value, to be inputted for a standard brightness region, which