CMYW Printing ????

[LuisF]

The Photoshop_Draconian_cmyw.jpg in the link below is the closest I can come close because the black and shade of gray were not converted to composite CMY black and gray.

https://www.dropbox.com/sh/66u3qyhzv9td ... EqQ2a?dl=0

[LuisF]

Here is the link to the description and detail about what I call CMYW file: https://www.dropbox.com/sh/66u3qyhzv9td ... EqQ2a?dl=0

[fmw42]

Here is the link to the description and detail about what I call CMYW file: https://www.dropbox.com/sh/66u3qyhzv9td ... EqQ2a?dl=0

There is no description there about the file format, only 3 images and you do not say what those images represent.

How do you know whether your image is proper or not. You must have a proper CMYW image to compare. So can you not upload that image so we can examine it.

[LuisF]

The output file New_Draconian_cmyw.jpg using your code is CMYK but the C and K are not swapped which cannot be used as CMYW. The CMY color can be viewed in Photoshop by hiding the K channel .The Photoshop_Draconian_cmyw.jpg is a CMYK that was modified by swapping C and K channels to work as CMYW that fools the printer to flood the CMY color of the image white toner. If you open the two output files in Photoshop you will see the difference. As stated in the description the CMY color can be viewed in Photoshop by hiding the C channel of Photoshop_Draconian_cmyw.jpg. I thought I clearly explained in the PDF file except I did not specify the format. Photoshop_Draconian_cmyw.jpg has cyan cast because the C channel has the negated data and that's what floods the CMY color with white toner.

BTW I tried Convert RGB_file -colorspace CMY cmy_file.jpg and the black was not converted to composite CMY black. Perhaps converting black with c=100%, m=100% and y=100% of RGB file. Is that possible? Photoshop does not change black to composite CMY using Change Color tool. It can only lighten or darken black.

[fmw42]

Why would you want C and K swapped. That makes no sense. C is cyan and K is black. If you want white then just negate the K channel. That is the command I gave above.

To help we need to see a proper CMYW image that is acceptable to your game or tool?

[LuisF]

The problem with that is K toner/drum set is the first set and C toner/drum set is last toner. The K channel data will be printed first instead of flooding the CMY color with K toner which is physically white toner in K cartridge. By swapping the C and K toner/drum set and matching swapped C and K channels the C data which is K channel is going to flood the CMY (C data which in K channel). It does not follow the CMYK order. I am trying to fool the CMYK printer to flood the CMY color with white toner and in a sense converting CMYK printer to a CMYW printer. It actually works but the black is not composite CMY black. Since the K toner cartridge is filled with white toner the black is not printed.

The physical order of toner positions in CMYK printer is 1) K, 2) Y, 3) M and 4) C. The physical order of true CMYW printer is 1) C, 2) Y, 3) M and 4) W. So by swapping the C and K toner in CMYK printer it follow the toner order of the true CMYW printer like Okidata 920WT except in the CMYK printer the K toner/drum set is filled with white toner. Having the K toner/drum set in the last position and C toner/drum set in the first positon matches exactly as true CMYW printer. The CMYK printer driver lays out the toner order in 1) K, 2) Y, 3) M and 4) C. So when the C and K toner/drum set are swapped the C data which is in K channel will be layed down first becasue it thinks that C toner drum set is K toner/drum set followed by Y, M and K data which is in C channel and the driver thinks it is C toner/drum set. Hence the CMY is flooded with white toner.

The method I am trying to develop is mimic what is done in the PDF file link below:
http://www.uninetimaging.com/downloads/ ... nt_ENG.pdf

Uninet system use CMYK printer to print the file and Swap the C and K toner to print CMYW file and it is printed in single pass.

As of not I can flood white on CMYK or RGB but it requires two passes. The color image is printed first. The K toner/drum set filled with toner is swapped with K toner/drum set filled with white toner. The printed sheet is feed back in the tray then a negated image of the color image is printed over the color image. This method is too slow and subjet to registraton issue. So print single pass is a better solution.

I hope I am making sense.

Luis

[fmw42]

Sorry, I still do not understand what order you want the channels. Do you want KYMC or WYMC or YMCW or WYMC?

If the latter, WYMC, then

Code: Select all

convert image_rgb -colorspace CMYK -separate +channel \
\( -clone 3 -negate \) \
+swap -delete -reverse \
-set colorspace CMYK -combine image_wymc

If you want KYMC, then

Code: Select all

convert image_rgb -colorspace CMYK -separate +channel \
-reverse \
-set colorspace CMYK -combine image_kymc

[LuisF]

The order I am looking for is KMYC. Prior to that conversion convert the CMYK or RGB input file's black to C=100% M=100% and Y=100%. Is that possible?

[fmw42]

try

convert image_rgb -colorspace CMYK \
-channel CMY -evaluate set 100% +channel \
-separate +channel \
-reverse \
-set colorspace CMYK -combine image_kymc

[helcite]

The order I am looking for is KMYC. Prior to that conversion convert the CMYK or RGB input file's black to C=100% M=100% and Y=100%. Is that possible?

LuisF, did you get this method working? I understand what you were attempting and I'm curious to know if you were successful.

Many thanks!

[LuisF]

I have not made it work successfully. I came close doing it in Photoshop but the printer driver always converts the CMYK to RGB and it messes up the cyan. The driver does not assign the remapped CMYK data to remapped printer channels. I don't know how to force the driver to keep the CMYK format. Anybody know how to customize printer driver or utility to keep CMYK data instead of RGB? Or is there a profile I can use?

Doing all the command line with ImageMagic the conversion creates a lot of artifact so I went back doing it in Photoshop. I am not putting down ImageMagic. It is a good software. I appreciate all the inputs and suggestions from everybody.