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Thread: JPEG Color Loss

  1. #1
    Join Date
    Dec 2009
    Location
    Prescott, Arizona
    Posts
    51

    JPEG Color Loss

    Hi All,
    I apologize if this question was already posted, but could not find it anywhere. One of my students who is on a MAC found that the when he saved as a jpeg there was quiet a bit of color degradation. Is this a known issue or does it have to do with a setting in ArtRage. I can not replicate it but I am on a PC and not MAC.

    Thank you for any help on this issue.

    Kind regard,
    Karen Bonaker

  2. #2
    Join Date
    Mar 2011
    Location
    Englishman in Ont, Canada
    Posts
    3,729
    I must be honest, i normally export from artrage as a psd but I just tried exporting as a jpg and then pulled it up as a preview to compare to the image open in Artrage and I do not see any difference.
    I am using an iMac.
    Geoff

  3. #3
    Join Date
    Dec 2009
    Location
    Prescott, Arizona
    Posts
    51
    Thank you for your response, which leads me to think it may be monitor or color settings, not sure.

    I will ask that he try a PSD as well and compare the two versions.

    Kind regard,
    Karen

  4. #4
    Join Date
    May 2009
    Location
    3438 ft above sea level
    Posts
    2,951
    Hi Karen
    This issue is inherent in the .jpeg filetype as it is a lossy filetype.

    The Joint Photographic Experts Group (JPEG) came up with the filetype as a solution to filesize and bandwidth issues that existed 15+ years ago. Given the computer capabilities back then, large format photographs were too massive in filesize to be sent around the world to editors etc over extremely small dialup bandwidths. Tape storage/Syquest storage etc was only around 40megs. The solution they came up with was the .jpeg filetype which provided massive compression with the tradeoff being quality.

    If you export out an image as a jpeg, import the file you exported and rinse and repeat several times you can demonstrate the quite dramatic loss of quality as each time a .jpeg is recompressed it will lose more of the image information.

    You can read up on this filetype here:-
    http://en.wikipedia.org/wiki/JPEG

    To solve the issue for your student get them to export to a lossless format such as .psd, .tiff, .bmp or .png.
    "I paint because I love to cut mats" (Arthur Alexander)

  5. #5
    Join Date
    Sep 2006
    Location
    New Zealand
    Posts
    719
    Hi guys

    I am the aforesaid Karen's student :-)

    The problem is that when export in any format (png and psd included) the saved image has become very much more saturated than the .ptg image.

    I am beginning to think that that it may be the way I have AR set up. I don't think AR has any colour management does it?

    I have also noticed (possibly related) that when I have a layer over a tracing image that layer is quite desaturated. If I toggle the tracing image on and off (using '/') then the image appears normal with it off and desaturated with it on.

    Brett
    Visit my gallery here.

    =========

  6. #6
    Join Date
    Mar 2006
    Location
    Ambient Design
    Posts
    3,504
    Hi Brett,

    When you have a tracing image, your painting will appear translucent as it's basically like working on a sheet of tracing paper over your tracing image. This will make it look more washed out. You can change the opacity of the tracing image in the tracing image panel, but you will always have this effect to some extent as your painting is not 100% opaque when a tracing image is visible.

    ArtRage doesn't do any colour management, so if the product you're opening the image in does, it may look different. Turning off colour management in the application you're opening the image in should give you the same result as in ArtRage.
    Dave
    Resident Bug-Hunter
    Ambient Design

  7. #7
    Join Date
    Sep 2006
    Location
    New Zealand
    Posts
    719
    G'day Dave

    I'm a Mac user and opening it in preview, AFAIK preview has no colour management.

    Thanks for the info on tracing. I guess I'll use layers rather than tracing. It would be nice to be able to lock layers though. Hint, hint!

    Something isn't right. I'll play some more and see if I can find out what's going on.

    Cheers

    Brett
    Visit my gallery here.

    =========

  8. #8
    Join Date
    Mar 2006
    Location
    Ambient Design
    Posts
    3,504
    If the image wasn't created on the Mac, then opened on the Mac, the colors may change due to differences in gamma on the Mac. If the image was created in ArtRage on the Mac then colors changed when viewed on the same Mac, color management of some sort is likely to be affecting it when viewed. It may be worthwhile checking Tools -> Assign Profile in Preview in case that's the cause.

    Otherwise, if the painting is less than 10mb in size, could you send a copy of it to me as well as the jpg to support@artrage.com so that I can compare them? If it's larger, could you crop it to a smaller area to reduce the file size, export that as a jpg to verify you see the colour shift and send me those files instead?
    Dave
    Resident Bug-Hunter
    Ambient Design

  9. #9
    Join Date
    Sep 2006
    Location
    New Zealand
    Posts
    719
    Hah! How many years have I been using Macs and I haven't seen the assign profile option in Preview. Oh well!

    Many thanks Dave, that fixed the problem. Once I switched to my own calibration of the monitor it was sweet.

    Cheers

    Brett
    Visit my gallery here.

    =========

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