On 28.05.2009 23:40, Hal V. Engel wrote: > On Thursday 28 May 2009 08:30:29 am H.Lekin wrote: >> Hello ! >> >> I joined this list to get some working-level advice on color management >> issues. Hope, this is an appropriate place. > > This might not be the best place for this. > Thanks a lot for the detailed reply.
All my color-managed software uses the Lcms library. This is why I skipped the GUIs for the programmer's CLI utilities. For any detailed information on how they work, this must be the best place...? > > just need to ask around. But the basic rule is if the print shop does not > understand CM and color matters to you then find a print shop that does > understand CM. > I use this copy(!) shop for years; very friendly and helpful people. I usually do my hard copies there. It was actually the first time that I came round with a file to use their color printer. Discussing the colors of the print, he asked me to bring a CMYK file. After I read through program documentation and quite some articles, I asked for the printer profile. This was as new to him as it was to me, but we are willing to get in to it. I think, there is also a print shop in town, but I am not sure whether they will be happy to do a single color print for me every now and then. > >> Also, some of my >> experiments yield strange, unexpected results. > > Also why do you think the results are strange. Have you calibrated and > profiled your monitor? Are you using a CM aware application to view the > results? If not there is no way that you can be sure that what you are > seeing > on the monitor is even remotely close to what it should actually look like. > I > am not saying that it is not close only that there is no way to be sure. > I used the ECI monitor test to adjust my monitor. I don't want to become a professional, I just dislike that on my print blue turns into green and wish to overcome this lack of understanding. In the viewing application, IrfanView, CM can be checked in the settings. It also lists the name of the embedded profile. >> >> I assume, the png I exported from Inkscape is based on sRGB color space. > > Why would you assume that? > Well, I had to start somewhere and I think it was the best guess: I made a drawing with the vector-graphics program Inkscape. The copy shop asked me to convert the Inkscape svg to jpg, png, tif or pdf. The png I can export from Inkscape has definitely no color profile included. As the print looks bad, the png is not in CMYK color space. For a color space transformation, I have to set an input profile and tifficc defaults to sRGB. What else should I have done? > > Actually you can check for an embedded profile in any recent version of GIMP > or cinepaint. No need for a hex editor. > I used a hex editor as I couldn't rely on anything. If I open the tif file with the embedded ISOcoated profile with Gimp, a message window pops up saying that this file contains the embedded color profile sRGB and whether I want to convert it to the standard RGB working space. If I choose to keep the embedded profile, Gimp insists on sRGB built-in and displays the image with great intensity (overcolored). On the other hand, Gimp's Separate plugin offers to keep the correct profile as source color space. The main disadvantage of this plugin is the lack of any tif compression, i.e. huge output files. > > Also if you know what color space the printer has then you can also use any > of > the above apps to create a soft proof that will actually come close to > showing > you what it will look like once it is printed. Of course this implies that > you can get the correct profile for the printer and that your monitor is > calibrated and profiled and so on. > As there is no printer profile available presently, and also because I may have to use an other printer, I decided to transform to a standard CMYK profile. Fist, to give me an impression of what my work will look like printed, and second, I thought that a standard CMYK color profile can be transformed to a specific machine color profile without a greater shift in color properties. Are these good assumptions? I want to do my part of what there has to be done before I go to the copy shop next time. Either I am happy with a straight print, or we have to find the machine profile and transform into it. Are these assumptions OK too? All I want is the blue not turning into green or other oddities. There is no need for colorimeter-precise colors. > >> If I use >> tifficc -e -oISOcoated.icc -t0 file.tif file-eCMYK.tif >> the result looks very much closer to the original RGB, just a little >> less brilliant. >> Is Embedding how things are supposed to be done? Always? > > The common processes are that the print shop tells you they want the > document/image in some standard color space like ISOcoated.icc because they > calibrate all of their printers for it (probably the most common for offset > printers). Or they want the document/image to have the color space(s) > embedded and they will convert it to the printers color space during their > printing process. Or the print shop will publish device specific profiles > that they want the document/image to be in and they expect you to do the > conversion (the last one is what Costco wants - probably the second most > common approach). > OK, you always [have to] embed a profile. In the beginning, I didn't use -e and even the soft proofs looked greenish. I thought that you do not have to embed the profile - read s.th. about tagging - if it is available on the system. This is not true? Is the command line above sufficient for what I want to do? What about 'precalculates transform' or 'black point compensation'? How do you use the -p option 'soft proof profile'? I transform the color profile and view the resulting file in a CM capable viewer. I consider this being my soft proof, right? Is there any FAQ for beginners? > >> Is ISOcoated_v2_eci to be preferred over ISOcoated (ECI, 2004), or do >> you suggest a different profile for my hobby case? > > I don't understand what you are asking here. You need to use the profiles > for > the devices you are using but many users convert all of their input devices > from the device color space to a generic working color space. Most color > savvy users now days use a medium to wide gamut generic RGB color space for > their working color space. This would include things like BetaRGB and > ProPhotoRGB. This of course assumes that you have created custom profiles > for > your input devices (scanners and cameras) and that you have calibrated and > profiled your displays and have valid profiles for your printers. > My input device is a vector-graphics program; no scanner, no camera. This e-mail became really messy. It might be better to break topics into pieces and start new threads... Thanks a lot for your help H.Lekin ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. 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