An amateur's advice on color management

Hi Everybody,
      This  post is intended as advice from one amateur photographer to another.  I hope that it doesn't step on an expert's toes.

1.  Use sRGB all the time for everything.  If you bring an Adobe RGB file or a ProPhoto file to the local supermarket, the prints will look washed out.  Ditto for the internet.  That even goes for fancy printing shops.  Just about nobody will know what you are talking about.  It's all about color "space".  (Color "space" is located in Outer Mongolia.)
2.  Stay with the default settings for everything.  Some very smart color scientists have worked everything out for you.  You will need a few college degrees in color just to understand them.. 
3.  Do not calibrate your monitor.  The International Color Consortium (ICM) has worked out how monitors work. Monitor manufacturers have tagged along.  If you change your monitor just to get some nice color on a poor photo, how is anyone else going to know what you did.

Now, just a tiny bit of instruction on color management for beginners who are curious about all the profile talk.  We'll skip the "color space" talk.

The problem is all about digital cameras, monitors, printers, scanners, and worst of all -- computers.  These guys have to communicate with each other to get your photo to the printer.
It would be very nice if your camera could just send a color swatch to the printer for each pixel.  Unfortunately, these guys can only pass around numbers.  So the camera starts off by giving each pixel three colors -- red, green and blue from which you can make about 16 million other colors.  So why can't the monitor and printer use these numbers directly if the ICM color scientists are so smart.  I don't know.  Let me know if you find out.  Meanwhile, the numbers have to be changed to get the same color on the monitor or the printer, etc. that the camera saw.

However, there is a standard numbering system worked out by the CIE back in 1932.  They gave each color three numbers (RGB).  Several derivative numbering systems were later worked out which are more convenient to use -- namely X,Y,Z and Lab. However, they are all based on the original numbers given to each color.
So here's the set up.



The camera or scanner sends its RGB numbers to the computer.  Within the computer is a "profile". This "profile" converts the camera's numbers to the numbers in Lab for each color for each pixel.  The computer then has to send some numbers to the monitor to create the voltages on each LCD pixel.  Again, for reasons that I do not understand, the Lab numbers have to be changed so that the monitor shows the same color as seen by the camera.  Again, this is done with a "profile".
   Ditto for sending the file to a printer.

If you can understand the above, then you are a lot smarter than me.  It took me years to get this far.

Phil

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  • I understand what you did here and it's kind of close, the scanner unless you use scanner software rarely embeds a profile. If you scan via Draw or PP after the scan you need to assign the scanner profile and in Draw assign the scanner profile then convert to the document color space.

    This is the 21st century so the camera may have a profile so use it, if not try sRGB, best to shoot  RAW.

    CorelDRAW picks up the monitor display from the OS, so this calibration is an OS Color Calibration application process.

    The low cost digital devices that are non-postscript are best left to sRGB, better quality devices may have a specific media profile that can be utilized in the color tab of the print dialog.

    A printing press profile is best when utilized as a non-device specific target profile with a TIC as close to the output media as possible. In reality just pick a CMYK profile that has a under color removal gray component replacement that you like and let the RIP handle it. I use 4 CMY profiles, one for sheath fed coated stock, TIC 360, one for sheet fed uncoated stock, TIC 280, one for web press coated stock, TIC 300 and one for web press uncoated stock, TIC 240.

    Under color removal, gray component replacement is a complex way of saying how the profile converts the CMY elements creating the gray balance and when the K component starts to be applied and how steep that curve is as well what percentage it maximum is.

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