Using of grey balance in Photoshop

The grey balance is a parity of quantities of the blue, purple and yellow colors, necessary for reception of neutral grey color. Such color is one of intermediate tones between cleanly white and black and has no undesirable superfluous color shade (that is grey color which is not perceived as pinkish or greenish as warm or cold). Without observance of balance of grey tones, the images printed with use of blue, purple and yellow printed paints, will have any undesirable superfluous color shade. Undesirable color shades can appear also owing to soiling of printed paints, an unequal degree of a dot matrix of points of printed paints of various colors, and also owing to a unsuccessful choice of sequence of drawing of printed paints or a wrong choice of corners of an inclination of a raster for the paints entering into the complete set.

Adjustment of Gray Balance, making in program Photoshop in dialogue window Printing Inks Setup, will help to avoid occurrence of superfluous color shades on the printed images. Adjustment is made with regulation scale of curves for blue, purple, yellow and black channels (CMYK). Each of channels of window Gray Balance (that is C, M, Y and) adopted by default a parameter of scale function 1.00, at a range of its possible changes from 0.50 till 2.00. The increase in some parameter in window Gray Balance leads to reduction in the image of a percentage share of a paint of the given color; reduction of index increases a percentage share of the given paint. For example, input in a line of M of a parameter, greater 1.00, reduces quantity of a purple paint in the image; input of a parameter, smaller 1.00, on the contrary, increases quantity of a purple paint in the image. As well as all adjustments Printing Inks Setup, adjustments of Gray Balance influence as representation of the image on the screen in the mode CMYK, and on results of conversion of the image from mode RGB into CMYK. Changes of adjustments of Gray Balance, executed during the work in the mode CMYK, influence only on new data added to the image, and will not affect on data which have been converted already for transition from the mode RGB into CMYK. To correct in program Photoshop unwanted superfluous color shades of images with using for this purpose adjustments of grey balance: obtain from a service bureau data for adjustment of parameters Gray Balance according to characteristics used there final excretory devices, enter these data into dialogue window Printing Inks Setup, then click Save. OR: Define parameters of adjustment of Gray Balance, using for this purpose a proof: 1. Print a proof of the test image: Ole No Moire (Macintosh), Testpict.jpg (Windows), or receive on the final output device any other trial image. For installation Photoshop for Macintosh file Ole No Moire is placed in folder Separation Sources enclosed in folder Calibration which in turn is in folder Goodies in folder Photoshop. For installation Photoshop for Windows the file Testpict.jpg is placed in subdirectory Photoshop \Calibrat. 2. Load Photoshop, then choose command File> Preferences> Printing Inks Setup. 3. In dialogue window Printing Inks Setup enter the size accepted by default 1.00 into fields Gray Balance for paints With, M, Y and To, then click button OK. 4. Open in mode CMYK the image simulating a trial printed print. 5. Choose command Image> Adjust> Levels. 6. Click Preview, then in emerging menu Channel serially allocate each of channels (that is Cyan, Magenta, Yellow, Black) and correct position of a moved regulator of scale in section Input Levels (an average toddler of grey color), while will not achieve, that the image on the screen corresponded to a proof. 7. Write down sizes of scale for each channel (that is numbers on the average a window of parameters Inputs - Levels); then click Cancel to close a dialogue window without change of the image. 8. Choose command File> Preferences> Printing Inks Setup. 9. Enter sizes of scale for channels into field Gray Balance; then click button OK if it is necessary to apply at once the established values, - or click Save to keep these adjustments in a file, for subsequent use.

NOTE: When you calibrate all your system, instead of simply balance of the separate image, all over again cancel the changes executed in dialogue window Levels; after that change the general grey balance of a program which Photoshop will use constantly for performance of conversion of colors: for it enter parameters of scale into fields Gray Balance of dialogue window Printing Inks Setup.