carol.gimp.org gimp2 Printing & Publishing

Publishing

License

Beta version of theGIMP Image Publishing Plug-in.

Printing

This is not about setting your printer up to print with TheGIMP and gimp-print; this is about making image files to be printed. My actual experience with printing image files is rather limited.

From the horses's mouth

I had what I remember to be a pleasant chat with a manager from a local Kinkos when in reality it was an interview for a job I did not get. What he said was that he had attended a day long seminar about how to covert rgb colors for their printers. The word was, let the printer (the actual machine) do the conversion for you.

By osmosis

My friend wanted to be considered a professional photographer. She always went the extra yard and read back ground material; showed up on time and did her taxes.

I think she was acting for a client to produce an image for an advertisement in a national magazine. She purchased the Photoshop7 with the fullblown cmyk ability. When she delivered her image to be printed, the printing company discarded her special cmyk image file and made the conversion for her from the rgb image file. The printing company had the profile for their printer and she did not.

The printing company had this crucial color information stored in a format that is native to the software they are using. Probably this software was installed with a one time calibration by people with colormetric equipment. This is my guess. I do not know what happens when you buy a printer that is $5000 or more....

I think also that it was simply because she was so personable and easy to talk to that the print company clerks explained it to her at all. If your job is to make good prints of things on a schedule, your job should not include needing to explain to clients the reason that they did not need to buy the seven hundred dollars of software.... I think that many times, the clerks are smart enough to get the original rgb file without getting into it with the print customer, so many people do not know that they are only mangling their image files when they do the conversion from "something that is understood" to "something that is a guess".

The moral: if you do not know vital color information from the destination of the image, you only need the rgb image.

By reading

Reading about color managment is gruesome. Vectors, vector spaces and commercial software. A lot of different people with a lot of different ways and names to describe color.

I am reading a mail list about it and not understanding word one about what is there. The people working on this color library are doing the exact opposite with software than I am accustomed to. I watch how software is made from the ground up; they are starting with up and running software and building it backwards.

I started reading web pages from a list I found on Norman Koren's Color Management site. The Art and Science of Printer Profiling has been very good. I am on page 7 of 14 as I write this.

This image was shamelessly stolen from one of the web sites I visited looking for color management information. If you have a Color Profile you are using with a software application on your images, either one provided by your employer or one you installed yourself, it might be a good time to locate which profile you installed on this simple flow chart. I will be honest. I grabbed a bunch of profiles from different places online and I have no idea what part in this flow the profiles are working in, or could be even....

Testcharts Displayed in this graphic is a testchart on a computer monitor and the same chart being printed from a printer. The samples used is a propietary difference. One uses evenly spaced patches with an emphasis on neutral, dark and light colors. The other approach is to optimize by their location within the color space. I searched the web for gizzmos that could read the color of your monitor and other gizzmos that could read the color from a piece of printed paper. I wrote a little script that uses TheGIMP's gradient editor to approximate the colors that occur between four colors.

Look Up Tables The colorimeter measures the color. This measurement can be located in the CIELab Colors. Now an ICC Profile can be made by mapping the color from the testchart to the CIELab color that the colorimeter read. I stopped reading here and searched for some tables. This is where I ran into binary files. Which means they are doing the simple math for you instead of sharing the information. At least, this is what I think is going on. I started to look for color sets and think about what I could learn by printing some test charts as photographs. Apart from holding the test charts up to the monitor, probably I would not learn much. Then I started to think about old magazines, well-known colors and scanners.