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Claims  |
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I claim:
1. A system for generating electronic signals representing an original
color video image for display in a conventional video signal color display
device such as a television receiver, said system comprising:
means for producing said electronic signals for display in response to
color value input signals;
first memory means coupled to said signals producing means and having first
memory elements, said first memory elements being constrained to store
only a representation of a single preselectable color value for display;
second memory means coupled to said first memory means and through said
first memory means to said electronic signals producing means, said second
memory means having second memory elements, said second memory elements
corresponding to matrix locations of said video image, said memory
elements being constrained to store only a representation of a single
preselected matrix image value which designates a single one of said first
memory locations; and
cursor means for manually generating said matrix image values in said
second memory means independently of said color values such that each one
of said image matrix locations is assigned a color value by reference to
said first memory locations.
2. A system according to claim 1 wherein each one of said matrix image
values comprises digital representations of memory addresses of a single
one of said color values and wherein said electronic signals producing
means is operative to scan said second memory elements and in response to
the matrix image values stored therein to generate a signal corresponding
to said color values stored in said first memory elements of said first
memory means.
3. A system according to claim 1 or 2 further including a programmed
microprocessor system coupled to said cursor means, to said first memory
means and to said second memory means, wherein said signals producing
means comprises a modulation and synchronization means and wherein said
first and second memory means are adapted to store said color values and
matrix image values in digital form.
4. A system according to claim 1 or 2 further including means for varying
said color values independently of said matrix locations of said video
image.
5. An apparatus according to claim 1 or 2 wherein said matrix image value
generating cursor means comprises a joystick coupled through said signals
producing means to said second memory means and operative to cause storage
of preselected matrix image values in said second memory elements.
6. A system according to claim 5, and further including analog-to-digital
converter means coupled to the output of said joystick; and means for
uniquely identifying output signals of said joystick with a pre-selected
operating interval of said joystick.
7. A system according to claim 1 or 2 wherein said signals producing means
includes an oscillator and a modulator for producing a modulated
television carrier signal adapted for coupling to input terminals of a
standard television receiver.
8. A system according to claims 1 or 2 further including means for
simultaneously generating an ordered visual display of all color values
stored in said first memory means.
9. A system according to claim 8 further including means for indicating the
selected one of said color values which is under control of said cursor
means.
10. A system according to claim 1 or 2 further including means for
identifying the location of said cursor means in the displayed color
image.
11. A system according to claim 10 wherein said location identifying means
comprises means for causing the matrix image element at the position of
said cursor means to alternate between a selected color and another color.
12. A system according to claim 1 or 2 further including means for
designating the image size of said cursor means relative to the overall
size of said video image.
13. A system according to claim 1 or 2 wherein said second memory means
comprises a serial shift register.
14. A system according to claim 13 wherein said second memory means further
includes auxiliary memory means for refeshing said shift register and
control means for synchronizing data in said shift register with
predetermined locations of said matrix image.
15. A system for generating electronic signals representing an original
color video image adapted for display in a conventional video signal
display device, said system comprising:
first memory means for color values;
second memory means for matrix image values uniquely designating locations
of said color values in said first memory means such that each element of
said matrix image is assigned a color value;
means for varying said color values independently of said matrix image
wherein said color value varying means comprises means for independently
adjusting the components of a color vector of each element of said color
values, the color vector comprising a hue value element, a saturation
value element and a luminance value element;
cursor means for manually generating said matrix image values in said
second memory means; and
means responsive to said values in said second memory means and said first
memory means for producing said electronic signals.
16. A system according the claim 15 wherein said color value varying means
are continuously variable.
17. A system according to claim 15 wherein said color value varying means
are discretely variable.
18. A system according to claim 15 further including means for transmitting
and receiving an audio signal representation of said matrix image.
19. A system according to claim 18 wherein said audio signal transmission
and receiving means comprises means for transmitting and receiving a
plurality of audio tones.
20. A system according to claim 18 wherein said transmitting and receiving
means further include an acoustic transducer for acoustically transmitting
and receiving said audio signals.
21. A system for generating electronic signals representing an original
color video image adapted for display in a conventional video signal
display device, said system comprising:
first memory means for color values;
second memory means for matrix image values uniquely designating location
of said color values in said first memory means such that each element of
said matrix image is assigned a color value;
means for digitally averaging the color values of consecutively display
image elements wherein said digital averaging means comprises a plurality
of parallel shift registers adapted to accumulate separate consecutive
digital values of each of the components of the color vector, means for
adding said digital values, and means for dividing said digital values to
produce a running average of said digital values;
cursor means for manually generating said matrix image values in said
second memory means; and
means responsive to said values in said second memory means and said first
memory means for producing electronic signals.
22. In combination with a television receiver, apparatus for producing a
color video image under manual control for display on the television
receiver, said apparatus comprising:
first memory means constrained to store a set of color values;
second memory means constrained to store a two-dimensional matrix image,
said matrix image comprising indices for uniquely identifying elements of
said color values set;
manually controllable means for registering said indices in said second
memory means;
manually controllable means for defining said color values of said color
values set independently of said matrix image;
means for generating a raster signal for defining a video resolution
element and for synchronizing the apparatus with the television receiver,
said raster generator including means for generating synchronization
signals and blanking signals for interfacing with the television receiver;
and
means responsive to first memory means containing said color values set,
said matrix image only through said first memory means and said video
resolution element generating means for generating a composite color video
signal at input terminals of the television receiver.
23. An apparatus according to claim 22 wherein said raster generator
further comprises means for producing horizontal line timing; means for
producing vertical timing; means for producing horizontal blanking in
synchronism with horizontal line timing; and means for producing vertical
blanking in synchronism with vertical timing.
24. An apparatus according to claim 23 wherein said raster generator
further includes means for generating a horizontal blanking interval; and
means for generating a reference color signal level during the second half
of said horizontal blanking interval.
25. A method for creating an electronic signal representation of a visually
displayable video color image under manual control comprising the steps
of:
preselecting and storing a set of codes representative solely of image
forming values in a first memory means, said values being independent and
without reference to location in said color video image;
generating values representative solely of a matrix image, said matrix
image comprising indices uniquely identifying locations of selected ones
of said image forming codes in said first memory means;
storing said matrix image values in second memory means; and
generating a color video signal in response to said matrix image and said
set of codes by causing a scanning of said second memory means to retrieve
said indices and in response to said indices to access a code so
designated and to generate a signal representative of said image forming
values at corresponding regions in said color video image for input to
input terminals of a video display means such as a television receiver.
26. A method according to claim 25 wherein said values generating step
comprises serially generating the indices by means of a remotely
controllable manual input means.
27. A method according to claim 25 or 26 wherein said values generating
step further comprises transferring signal representations of said indices
to said second memory means in response to an audio frequency encoded
signal.
28. A method according to claim 25 for indicating the position in the
displayed matrix image of a values generating step representing a cursor,
said method comprising the steps of:
storing the matrix image value corresponding to the cursor current position
in a temporary memory loaction set aside for the current position;
comparing previous and current matrix values at the corresponding location
is said second memory means to detect a change in said designated
position;
transferring the current selected color value to said second memory means
and periodically substituting for a brief interval a nonselected color
value for the current selected color value in said location of said second
memory means and periodically restoring the current selected color value;
and,
upon detection of movement of the cursor away from the current position,
finally transferring a further designated color value to said
corresponding location in said second memory means.
29. A method according to claim 28 wherein said final transferring step
comprises storing the current selected color value in the designated
location of said second memory means.
30. A method according to claim 28 wherein said final transferring step
comprises restoring the previous selected color value to the designated
location of said second memory means.
31. A method according to claim 25 or 26 wherein said first and second
memory means are digital and are stored in digital form in said first and
second memory means.
32. A method according to claim 25 or 26 further including the optional
step of automatically generating a matrix image consisting of only one of
said color values.
33. A method according to claim 25 or 26 further including the optional
step of simultaneously generating an ordered visual display of all color
values stored in said first memory means.
34. A method according to claim 33 further including the step of indicating
the selected one of said color values.
35. A method according to claim 33 further including the step of restoring
matrix image values upon termination of said step of generating all color
values.
36. A method according to claim 35 comprising the steps of separately
accumulating consecutive digital values of each component of said color
vector, adding like components, and dividing the sum by the number of
values accumulated to produce a running average color value for generation
of a video image.
37. A method for creating an electronic signal representation of a visually
displayable video color image under manual control comprising the steps
of:
storing a set of color values in a first memory means;
generating values for a matrix image, said matrix image comprising indices
uniquely identifying locations of said color values in said first memory
means;
storing said matrix image values in second memory means;
adjusting the components of the color vector of each of said color values
independently of the matrix image, the components of the color vector
comprising a hue value element, a saturation value element and a luminance
value element; and
generating a color video signal in response to said matrix image and said
set of color values adapted for input to input terminals of a video
display means.
38. A method for creating an electronic signal representation of a visually
displayable video color image under manual control comprising the steps
of:
storing a set of codes representative of image forming values in a first
memory means;
generating values for a matrix image, said matrix image values comprising
indices uniquely identifying locations of selected ones of said codes in
said first memory means;
storing said matrix image values in second memory means;
digitally averaging color vector components of consecutively-ordered image
forming elements over a defined interval; and
generating a color video signal in response to said matrix image and said
set of codes and averaged color vector components for input of an image
having enhanced image definition of consecutively-displayed image element. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates to home entertainment devices and particularly to
color video image generation and display simulating an artist's painting.
II. Description of the Prior Art
Video graphic display devices are well known in the computer arts.
Relatively sophisticated graphic display devices which interface with
large or medium-sized computers through a keyboard have long been
employed, and they find wide application in data processing and
information display. However, the expense and sophistication of the
computer-based systems with which graphic display devices have been
employed as well as the sophistication and data storage requirements
believed to be necessary to generate video displays, especially color
video displays, has substantially limited use to scientific, technical and
commercial applications, such as graphic design and information retrieval.
Relatively inexpensive interactive video display devices have recently been
introduced for home and arcade entertainment. A representative patent
describing the technology is U.S. Pat. No. Re. 28,507, dated Aug. 5, 1975.
Microprocessor-based video entertainment devices have also been developed
for home and arcade entertainment including color display features.
However, such entertainment devices embody a design philosophy exclusively
directed to the implementation of simulated competitive games, usually
involving the striking of a moving object such as simulated tennis, hocky,
football, baseball and warfare. To date, no system has been designed which
permits a human user to remotely paint a multi-color video image from a
font of user-mixed colors in the manner of a brush artist.
SUMMARY OF THE INVENTION
The invention comprises a home entertainment system which synthesizes color
images in a manner simulating the use of the palette of an artist, thereby
permitting a user to remotely paint pictures on a conventional television
screen. As such the invention is embodied in a new artistic medium. The
apparatus according to the invention comprises an input unit including a
joystick, an image or picture element memory, a palette or color memory
controllable independently of the image memory, and color television
signal generating circuitry. The palette is either an analog or a digital
signal memory device which is operative to store a value representing a
source color and specifically all of the components of a source color,
such as hue, saturation and brightness or red, green, and blue color
values. The image memory is a digital signal memory device which is
arranged in a matrix corresponding to coordinates on the viewing screen in
general in cartesian coordinates derived from a standard television raster
image.
In operation, a color index or "pointer" is selected by the input unit
which in turn generates signals which are stored in the image memory. The
image memory registers the color index in its matrix without reference to
the actual color value. Instead, the index identifies the color to be
generated at the selected matrix location. The color television signal
generating circuitry decodes the value of the identified color and
synthesizes an image as a synchronous signal provided to a television
receiver or video monitor.
The image generator according to the invention includes a number of
features enhancing the practical utility of the apparatus. An image is
generated on the image viewing screen by a "brush" which is controlled by
a remote joystick controller. In order to identify the current location of
the static brush, a mechanism is provided to cause the current brush
location to be displayed. The display is preferably of a blinking or
flickering at the current brush location on the screen.
As an aid to blocking in large areas of color simultaneously, the brush
control mechanism includes the capability of increasing the effective size
of the brush location. The brush shape is preferably an "L", thus
extending both the vertical and the horizontal sweep of the brush during
use.
The apparatus further includes a capability for separately displaying all
available colors simultaneously, called a palette, for adjustment of the
color values. The available colors may be displayed overlaid on the image
during image generation without affecting the final image, and the
selected brush color is preferably displayed distinctly from other colors
in the palette.
The apparatus includes a capability of electronically recording and
subsequently reproducing a signal representation of an image with
virtually any inexpensive tape recorder by means of simple acoustical
coupling.
A particular preferred embodiment of a color memory system has an image
matrix with a resolution approaching the resolution of conventional color
television yet which is transmitted within the bandwidth limitations
imposed by broadcast television standards. The preferred memory system
digitally computes a color average of fixed transient response time. The
average is used to drive digital to analog converters which generate the
displayed television signal.
The use of two memories to synthesize a color image has numerous
advantages. First of all, it allows the use of less expensive memory
components of smaller memory capacity. Second, it enhances the throughput
and thereby the resolution of the matrix without adding substantially to
the overall system cost. Third, the use of a separate color memory enables
all colors identified by a single index to be modified simultaneously
withough disturbing the contents of the picture matrix memory. Fourth, in
band limited data transmission between subsystems, the use of a separate
memory reduces the bit rate required to fully describe each picture
element.
The palette display and remote brush blinker feature of the invention
greatly enhances the practical utility of the invention in a more natural
man-machine interface. In the high resolution embodiment herein described,
the digital averaging and fixed transient feature prevents color staining
of adjacent displayed memory locations.
Other advantages and object of the invention will be set forth in the
following detailed description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a first embodiment of the invention.
FIG. 2 is a perspective view of the second embodiment of the invention.
FIG. 3 is a block diagram view of system according to the invention.
FIG. 4 is a detailed block diagram view of the first embodiment of the
invention.
FIG. 5 is a block diagram view of a second embodiment of the invention.
FIGS. 6A and 6B are together a detailed block diagram in partial schematic
of the second embodiment of the invention.
FIG. 6C illustrates the manner in which FIGS. 6A and 6B relate.
FIG. 7 is a block diagram of an image record and recreate feature of the
invention.
FIG. 8 is a block diagram of a modification to the embodiment of FIG. 6 for
producing high resolution images.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
According to the invention, a manual image generating system is provided
which, in conjunction with a conventional television receiver, or video
monitor, electronically reproduces colored images created by an artist
manipulating an electronic paint brush and a palette of colors. A
principal feature of the invention is an electronic palette or color
memory which is controllable independently of an image storage device or
picture memory. Two principal embodiments described herein differ
principally in the form of color memory. In one embodiment, an analog form
of color memory is utilized. In a second embodiment, a digital form of
color memory is utilized together with a microprocessor interface control
with a picture memory. Alternatively, discrete logic may be used for
interface control. In addition, means are provided for recording the image
on magnetic tape through an acoustic audio coupling which can be used with
any conventional audio recorder such as a tape recorder.
Turning to FIG. 1, the principal components of one embodiment of the
television manual image generating system are illustrated pictorially. The
system comprises a television receiver 10, a control unit 12 and means 14
for connecting the control unit 12 to the receiver 10. The receiver 10 may
be any of the standard commercially available color television receivers
provided with antenna input terminals 16. The connecting means 14 may be a
twin lead or cable and is preferably a shielded coaxial cable
appropriately matched to the impedance of the input terminals 16.
Alternatively, the output signal may be a composite video signal, and the
display device may be a television monitor. The present invention is
described as it would be amenable to cost critical applications such as
video recreational products for the consumer market. However, the novel
features of the invention can be extended to the synthesis of color
graphic displays by suitably modifying the memory size, bandwidth and
system interface.
The controller 12 comprises a console with various control input devices on
the face thereof. The control devices generally include an x-y analog
proportional movement transducer or joystick 32, a color selector switch
34 and color palette controls 36, 38 and 40. The control unit 12 is
capable of generating signals for producing a set of colors, each color
corresponding to a "well" of an artist's palette. The control unit 12
presents the user the manual control functions for the "wells" in a
variety of ways. For example, the "wells" may comprise a bank of knobs,
with three knobs corresponding to the independent components of the color
vector of each "well" of the electronic palette, namely hue, saturation,
and luminance or brightness. Alternatively, the knobs could represent
additive primary colors such as red, green and blue. In the invention
described in FIG. 1, palette "well" controls 36, 38 and 40 provide hue,
saturation and brightness control for seven "wells" of color.
FIG. 2 illustrates an alternative embodiment of the controler 12'. In
addition to a joystick 32 the control interface may comprise five double
throw center-off switches 42, 44, 46, 48 and 50, and four push buttons 52,
54, 56 and 58. Three of the double throw switches 42, 44 and 46 control
adjustment of the primary colors, red, green and blue. Switch 50 controls
the mode of operation of the joystick 32, i.e., between "paint" and
"sketch" mode. The paint mode causes a stored image change, while the
sketch mode causes a transient change which is displayed but not stored.
Push button 52 provides either a display of the image or a momemtary
display of palette colors superimposed on the color image. The other
switches are provided for other selective operations of the controller
12', such as "one color" (switch 54) a function which "paints" the entire
display screen with the selected color, "record" (switch 56) and
"recreate" (switch 58), and "palette" (switch 52), as hereinafter
explained.
In order for the user to produce an image, he merely selects the color
(switch 48) which is adjusted to taste (switches 42, 44, 46), and then
manipulates the joystick 32 to "draw" a swath of color onto the screen 18.
The user, like a brush and paint artist, has complete flexibility in color
adjustment and in image placement. The user may select the palette mode
(switch 52), "mix" the colors with switches 42, 44 and 46, and then paint
with the freedom of a brush artist.
In addition, means are provided for recording the image 18 which is created
and displayed on the screen 20 of receiver 10. The image recording means
comprises a recording controller 22 internal to the cabinet of display
controller 12, pickup 24 (a microphone) and an audio recorder 26 such as a
conventional cassette recorder. The pickup 24 is coupled through a
shielded cable 28 to the recorder 24, which records an audio frequency
representation of the color video image. The recording controller may also
include an input means 25 such as a microphone for receiving the recorded
signal and recreating the recorded image. These functions may be
controlled by the record and recreate switches 56 and 58.
THEORY OF OPERATION
The theory of electronic painting as herein described is now set forth.
Referring to FIG. 3, there is shown a block diagram of the basic system.
The system comprises an input/output (I/O) unti 60 coupled to a control
unit 62. Control unit 62 is coupled through a bus 63 to a picture memory
64 and to a color memory 66 and through timing lines 65 to the picture
memory 64, to the color memory 66 and to a color generator 68. The picture
memory 64 is functionally coupled through the color memory 66 to the
generator 68. The I/O unit 60 comprises the manual controls such as the
joystick, switches and/or manually adjustable potentiometers illustrated
in either FIG. 1 or FIG. 2. The control unit 62 includes basic timing and
synchronization circuitry for all subsystems.
FIG. 4 illustrates a first embodiment described briefly in connection with
FIG. 1. The embodiment of FIG. 4 is characterized by a digital picture
memory 64 and an analog color memory 66. The picture memory 64 comprises
an array of dynamic shift registers in a picture matrix memory 80 and in a
line refresh memory 81. The picture matrix memory 80 is a 1024.times.3 bit
dynamic shift register. (Alternatively, a random access memory (RAM) may
be used.) The analog color memory 66 comprises an array of seven
potentiometer stacks of three potentiometers 36', 38' and 40' with
associated circuitry.
As hereinafter explained, the setting of each potentiometer determines the
analog value of the color to be reproduced.
According to the invention, memory locations of the picture matrix memory
80 are associated with unique locations or picture elements (pixels) of a
video image. The digital values in each matrix memory location merely
index or point to one of eight unique color values stored in the color
memory 66, the values of which are conveyed, upon signal, to the color
generator 68. The color generator 68 processes the values to create a
composite video signal to be conveyed to input terminals of a television
monitor.
The following is a description of the various subsystems and their
operation.
ANALOG MEMORY VERSION
Referring to FIG. 4, the control unit 62 comprises a raster generator 70, a
system clock 72 and a data justifying counter 76. The system clock 72 is
coupled to each of the subsystems of controller 12 and is, for example,
operative to produce clock pulses at the NTSC standard chrominance
subcarrier frequency, specifically 3.579545 MHz. The raster generator 70
generates a 262 line non-interlaced synchronization format by dividing the
basic clock frequency by 228 to produce horizontal line time and by
further dividing the frequency of the horizontal line time by 262 to
produce vertical timing synchronization.
Each image is generated by horizontally scanning 240 lines separated by
equal vertical intervals. A vertical blanking interval consuming a total
of 22 lines is set aside for synchronization and other functions as
hereinafter explained. Horizontal blanking is selected to consume
approximately 10 microseconds. A further clock signal, designated the
matrix clock output 78, is derived from the raster generator 70 and
provided to the data justifying counter 76 and to the picture matrix
memory 80 of the picture memory 64.
In the operation of the raster generator 70, two signals are produced
during each horizontal blanking interval of a picture generating sequency
(or line). During the first half of each horizontal blanking interval, a
horizontal composite synchronization pulse is generated and fed to the
composite sync line 82. During the second half of each horizontal blanking
interval, a reference color burst pulse is generated in color controller
88 and applied to modulator 86. At the end of the active picture portion
of frame, i.e., after all lines have been displayed and the cycle is ready
to repeat, but during the vertical blanking interval between active
picture portions, a vertical synchronization pulse is provided to sync
line 82.
The vertical synchronization pulse generally has a duration of three to
four horizontal lines. During the vertical synchronization interval, color
bursts are eliminated and horizontal synchronization pulses are lengthened
by approximately ten times. In addition, composite blanking signal are
provided through blanking line 84 for the duration of the blanking
intervals. During transmission of the blanking signals, the luminance
signal output is clamped to the black, or zero, signal level to prevent
interference of chrominance signals with synchronization signals. Both the
composite sync line 82 and the composite blanking line 84 are coupled to
the radio frequency modulator 86 which forms a part of the color generator
68 hereinafter explained.
The picture matrix memory 80 stores the picture data in a recirculating
sequence. The picture data requires 768 locations of memory.
In the present embodiment a 1024(1K) location memory of 3 words is
utilized. The picture data is thus 256 stages short of exiting the shift
registers at the end of the active picture portion of the frame. In order
to advance the data through picture matrix memory 80, a data justification
counter 76 activates a data justification clock via line 83 during the
vertical blanking interval as signaled through line 85 from the raster
generator 70. The data justification clock 83 thereupon advances the data
serially through the memory until the data is ready to emerge. The rate of
the clock 83 is proportioned so that data is justified in the time
available to minimize data retention problems due to excessive hold times.
This generally means that the clock is slowed relative to the matrix clock
78.
To avoid a requirement to store redundant information in picture memory 64,
having fewer vertical elements than storage location in the matrix, a line
refresh memory 81 is provided. The refresh memory 81 is operative to
recirculate identical data to make up the vertical dimension of the
resolution cell. Where a 32 by 24 matrix is employed, the line refresh
memory 81 is operative to recirculate data for 10 lines to achieve the 240
line output of the video image.
The picture memory 64 includes within its subsystem a 10-bit register (not
shown) which is used to define the instantaneous matrix address of the
resolution cell data being transmitted. In operation, the five least
significant bits (LSB) are clocked at the matrix clock rate, and the five
most significant bits (MSB) are clocked at 1/10th of the matrix clock
rate. The five LSBs define the column clock and the five MSBs define the
row clock. The column clock signal is derived from the master clock signal
through a divide by 6 counter (not shown) and the row clock is provided
though a synchronous divided by 10 counter driven by the row clock.
The line refresh memory 81 is used to enter new data into the picture
matrix memory 64. New data is derived from the 10 bit brush position
comparator 74, which generates a strobe signal through line 186 to line
refresh memory 81. In operation, the strobe signal persists for the
duration of one resolution cell and is repeated for each line scan during
composition of that particular cell. In this manner, the brush "stroke" is
used to selectively load new data into the picture matrix memory 80.
Brush position comparator 74 is under the control of the I/O device 60. The
I/O device 60 comprises joystick 32 coupled to a brush motion generator
89. The joystick generates analog signals in response to change in
azimuthal position. These signals are provided to a brush motion generator
89 which comprises two analog-to-digital converters (ADC), one for
converting motion in the horizontal direction to a five-bit digital value
and the other for converting motion in the vertical direction to a
five-bit digital value. A brush register (not shown) within the generator
89 temporarily stores the horizontal position value as the five least
significant bits and the vertical position value as the five most
significant bits.
The design of each of the generator ADCs is identical. Both comprise
relaxation oscillators whose outputs are connected to binary counters each
of which forms half of the brush position register. In operation, the
relaxation oscillators are gated on only during the vertical blanking
period such that the brush position register 74 contains a count at the
completion of the vertical blanking period which is proportional to the
frequency of the corresponding relaxation oscillator. The signals from the
joystick 32 are derived from potentiometers associated with each axis of
the joystick 32. The potentiometer forms a part of a resistance-
capacitance timing network defining the time constant of the relaxation
oscillator. The period of oscillation of the relaxation oscillator is
therefore directly proportional to the potentiometer position.
Multiple position switch 34 (FIG. 1) is used to select the color to be
painted from among the palette colors. Specifically, each position of the
multiple position switch 34 corresponds to the combined selection of one
hue palette control 36, one saturation palette control 38, and one
luminance palette control 40. The position of the respective palette
controls 36, 38 and 40 determines a resistance value of a potentiometer
stack 36', 38', 40' (FIG. 4) of color memory 66. The resistance value of
the individual potentiometers comprising the stack are directly
proportional to hue, saturation and luminance information and are
therefore adjustable to the user's taste independent of image location.
The color generator 68 incorporates a modulator 86 and radio frequency
oscillator 87 with a color memory controller and adder 88 (FIG. 4). The
circuitry of subsystem 88 shares common circuitry with color memory 66
such that it derives signals from potentiometers 36', 38', 40' to generate
a composite video signal.
Chrominance signal generation is carried out in three phases corresponding
to the generation of the hue, saturation, and luminance information
forming the three components of the color vector. Unit 88 includes a
"one-shot" multivibrator (not shown) which is triggered once every cycle
of system clock 72 through line 90. This first "one-shot" multivibrator in
turn is coupled to a second "one-shot" multivibrator (not shown). Hue
adjustment is provided by varying the period of the first one-shot
multivibrator while in turn triggers the second multivibrator which is
operative to generate a symmetric square wave at the system clock
frequency, the phase of the second multivibrator being controlled by the
variable period delay for the first multivibrator.
The selected hue adjustment potentiometer 36' is operative to control a
variable period delay of the first multivibrator of unit 88 during all
periods of color generation, except during the reference color burst the
potentiometer 36' is shunted such that the first multivibrator generates
its minimum time delay signal.
An "L pad" type attenuator (not shown) is included in unit 88 to effect
saturation adjustment. Saturation adjustment is the amplitude control of
the chrominance signal. The selected saturation adjustment potentiometer
38' forms the shunt leg of the "L pad" attenuator.
Similarly, an "L pad" type attenuator (not shown) is provided in unit 88 to
control luminance information, the luminance potentiometer 40' forming the
shunt leg of the "L pad". The luminance information is provided as
follows: during blanking periods, a black level in the video signal is
set. At all other times the selected luminance potentiometer 40'
establishes an instantaneous DC level which is conveyed on the video
signal.
The particular combination of luminance, chrominance and hue values which
are transmitted in the video signal is selected electronically by
transistor switches (not shown) activating the hue, saturation and
luminance adjustment. The picture matrix memory 80 is scanned
electronically to activate three signal lines 92, which are binary coded
to activate one set of hue, saturation and luminance control in unit 88,
that is, the signal lines 92 are decoded so as to select the particular
color control potentiometer identified by the unique address thereof in
the picture matrix memory 80.
The luminance signal and the chrominance signal are added by means of a
resistance capacitance network (not shown) and applied as a video signal
to modulator 86. An r.f. oscillator 87 provides a carrier signal to
modulator 86. The source of the radio frequency signal may be a simple
one-transistor oscillator circuit (not shown) of conventional design
arranged to oscillate at either 61.25MHz or 67.25MHz. A front panel switch
or the like, such as switch 94 (FIG. 1), is provided to select the
frequency of oscillation and thus the channel. Modulator 86 comprises a
suitably biased diode arranged to conduct more heavily in a forward
direction and thereby to transmit more radio frequency signals for video
signals which approach the DC level of composite synchronization pulses
provided through signal line 82. The consequently modulated radio
frequency signal is fed to a radio frequency filter/transformer (not
shown) or the like which in turn provides appropriate impedance
transformation to make the modulate radio frequency signal available to
the input of a standard television receiver.
In order to assist the artist in visualizing the colors to be reproduced,
suitably arranged switches are provided to synthesize a persistant brush
strobe of one color ("one color" mode). For example, a switch control 96
(FIG. 1 and FIG. 4) may override the output of the brush strobe line 186
to synthesize a persistent brush strobe which blankets all memory
locations of the color memory 64 with the same color index. Switch control
96 is therefore useful in painting backgrounds.
A "sketch" mode control switch 98 (FIG. 1 and FIG. 4), initiates signals
which directly control the color selection 92, without disturbing the
composite image stored in the picture matrix memory 80. When used in
conjunction with the one color button control 96, the sketch mode
controller 98 may be used to preview a color selection of the entire
displayed image without disturbing the composite image stored in picture
memory 80.
DIGITAL MEMORY VERSION
Turning now to FIG. 5, there is shown an embodiment of a manual image
generator or video controller 12' (FIG. 2) characterized by use of a
programmable control system and an addressable digital color memory. In
block diagram form, the controller 12' comprises an I/O unit 160, a
programmable microprocessing unit (MPU) 162, a picture matrix memory 164,
a digital c | | |
