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For those of you who want to make color-accurate raw scans (steps to take)
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PrimeGoat:
Hello,
To everyone who posts raw scans here: Please be aware that one of the issues with copying (scanning+printing) is color matching.
I'm sure that you're all aware that if you try to copy something, the colors will always be slightly off. This is because every graphical input and output device all have their own understanding of colors.
Because of this issue, and to deal with this issue, exist the science, art, and business of color management. I've looked around on the forum here and haven't found any real discussion about this, so I'll take the lead. It IS possible to create VERY accurate colors in your copies, without any of the guesswork involved in printing multiple strips of colors and manually picking which ones match, etc. However, in order to do this, people who make and post raw scans need to take certain steps to make this possible.
For those of you who are dedicated scanners, I recommend you buy an IT8 color target, which you can then use to profile your scanner. You can get some high quality ones for cheap over here: http://targets.coloraid.de/
The way this works is that you scan the target and then use color profiling software to analyze the scan, find the difference between the scanned color and the actual color of the paper (the colors on the color targets are standardized, and include files with the real LAB color levels), and then generate an .ICC profile for that particular scanner, which turns any scan it makes into a color-accurate scan. This is the first step to making color-accurate copies (the printer will have to be profiled too, through a different process).
I will be posting a guide on profiling your scanner in the future, or you can find one yourself on Google. The main point here is to be aware that if you want real accuracy, you're gonna want to get your scanner profiled and the colors calibrated.
There is also an alternative to doing the calibration yourself. However, for this to work, we need to standardize the scanning process. I saw that there's a thread with a guide on scanning. It is nice, but I have information that can supplement it, so I will work on a more in-depth scanning guide. In the meantime, I will say that the best software to use for scanning are VueScan and SilverFast. They are specifically designed for creating top quality RAW scans.
If you're not going to profile your scanner and include an .ICC profile with your scans (or convert the scan, using your profile, over to sRGB), then the next best thing you can do is to include sufficient information with your scan so that someone else can take the necessary steps to calibrate the colors in your scan. With that information, someone else who happens to have the same scanner as you will be able to create an ICC profile for it and will then be able to apply it to your scans, and hopefully share the .icc file with you too :)
Your scans can then be re-released with their colors calibrated into the sRGB colorspace.
Here's the information you should include with your scans:
* The scanner model you used.
* Which ICC profiles (if any) were applied to your scan.
* Which software you used to make the scan, and which version. Remember, VueScan and SilverFast are the best options.
* The exact settings that were used in the scanning software to make your scan. It's always best to use the settings that create a RAW scan without any sort of filtering. SilverFast does have some decent descreening filters. It's ok to use this. The main thing is to know what you're doing so that your filtering won't mess up someone else's ability to do a better job by preventing them from accessing your scan unfiltered. The OTHER main thing is to not use ANY color correction filters at all. If it changes the colors, don't use it! The only color 'correction' that will have any real benefit will be the actual color management and ICC profiles that this post is talking about.
* The exact settings that were set for your scanner in the device driver settings. If you have the choice, be sure to set it to disable all built-in filtering and color correction, and disable all color management (we will be doing our own color management, and doing it arbitrarily can only mess things up). Also keep in mind that many higher end scanners come with their own ICC profiles. In my experience, (Epson V600) these weren't that accurate and I had to profile it myself to get a good result. Do NOT apply any profiles. Instead, include the .icc files with your scan and let the users of your scan decide on their own what they'll do with it.
This will allow the scans to be color-accurate on some level (either already accurate, or leaving the possibility for later calibration). For anyone who wants to use color-management to have the best color accuracy for their scans (and by extension, their prints), I can help you with the process. I intend on posting a more detailed guide in the near future. In the meantime, feel free to reply to this post or PM me if you have any questions.
Keep in mind that color-accurate scans are only part of the process. You'll also have to print these color-calibrated scans with a color-calibrated printer. This will be a topic of future discussion. In the meantime, it's best to be proactive and ensure your scans are proper, so that when the time comes to calibrate your printer and do the printing, the actual source material will have the correct colors.
Also, be sure to save your scans in a lossless format. This can be either .png or .tif. NEVER use JPEG, as even at top quality settings it will still be lossy.
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