Defects in an image forming system may give rise to visible streaks, or one-dimensional defects in an image that run parallel to the process direction. One known method for compensating for streaks introduces a separate tone reproduction curve for each pixel column in the process direction. A compensation pattern according to this invention has a plurality of halftone regions that are lead by, trained by, and separated by rows of fiducial marks. The fiducial marks allow the printer pixel grid and a scanning pixel grid to be correlated. The gray level in each pixel column of each gray level portion is measured and analyzed to produce a local tone reproduction curve for each pixel column and associated line width. The local tone reproduction curves are then used to compensate for the streak defect when printing.
Apparatus are provided, including a macrouniformity compensation mechanism to modify data exchanges between device-independent image data and a one-dimensional imaging device, to compensate for a lack of macrouniformity caused by the one-dimensional imaging device. The macrouniformity compensation mechanism includes an input-output value converter to convert an input intensity value for a given pixel to a corresponding output intensity value. The output intensity value is determined as a function of the position of the given pixel in the cross-process direction of the image and the level of the input intensity value. The input-output value converter includes a number of stored conversion parameter sets corresponding to respective different positions in the cross-process direction of the pixel data. The number of stored conversion parameter sets is a fraction of the total number of pixel positions in the cross-process direction of the pixel data.
Conventionally, acquisition of color values from a color chart takes substantial labor and time. According to this invention, when the color value of each patch composing a predetermined line is input with each line of the color chart composed of a plurality of patches as the measurement unit, a measured line identification processor determines whether or not said line to be measured was measured in the predetermined measurement order, a warning section performs a predetermined warning processing if the measurement order for said line to be measured is no to correct, and when a color value acquisition line correction instruction is input to correct a line whose color value is expected to be acquired in said measurement order, a color value saving section makes the color value of said input each patch correspond to the gradation value of each patch composing said line to be measured.
A method enables an ink jet imaging device to normalize the driving signals for the ink jets within a print head of the device. The method includes generating an ink jet driving signal at an initial voltage and a particular resolution, coupling the ink jet driving signal to an ink jet for selective emission of ink from the ink jet in accordance with the driving signal, and detecting whether continuity for a line formed on the ink receiver by the emission of ink from the ink jet is substantially continuous.
