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Thread: Photoshop problem: pixelated RAW preview image

  1. #1

    Photoshop problem: pixelated RAW preview image

    for some reason when i import and image from my 5d that i shot RAW, after it goes through the preprocessing window that opens after double clicking, the picture looks pixelated. The picture is the same size as it was in the pre processing window but in the photoshop window its all pixelated and the edges look rough. once i zoom a tad this goes away but i dont know why when its zoomed out it looks this way. hope that makes sense

  2. #2

    Join Date
    Dec 2008
    New Zealand
    Real Name
    Have a guess :)

    Re: photoshop question

    Hi Caspill,

    Possibly what you're seeing is the embedded JPEG thumbnail whilst your PC converts and displays the actual RAW file a short time later?

  3. #3

    Re: Photoshop problem: pixelated RAW preview image

    nevermind! this doesnt show up in the finished file its just because its so small i guess

  4. #4
    Davey's Avatar
    Join Date
    Sep 2008

    Re: Photoshop problem: pixelated RAW preview image

    Seems to make sense to me. I'd guess it's because of the way pshop is showing the image. If you zoom to 20% then for every 5 pixels only 1 is visible as you will have guesed. I'm unsure of the mechanics of exactly how pshop chooses what to show and what not to but the way it does this quick and on the fly is far from perfect is my guess hence it won't take time iterpolating and averaging data from surrounding pixels and prob just simply disappears them when zoomed out hence looks crumby. To do anythign else is a waste of computing power but I'm sure there is a way to change this if you're really unhappy with the behaviour. A lot will depend on your monitor and res you work at, things like that tend to look much worse at lower res especially on a big screen and the res is significantly lower than the recommended default one for that screen size.

    Why the acr preview isn't doing that is probably less to do with image source and more to do with way it renders it. Delving a bit more into it I suppose you never see the raw file directly but rather in one case you see a compressed preview (smaller too etc in the case of the embedded jpeg) but acr preview is a bit different and isn't the embedded jpeg. Obviously you never see the "actual" raw but we will call the none embedded jpeg preview the actual image for ease of discussion. I'd guess what you see is a generated on demand image but should look (more or less) identical to the one opened to work on in pshop, obviously the one opened to work on is generated from the raw data more accurately than the acr preview (hence takes longer to generate). Considering this it's clearly not the source or processing of it that is degrading it so by inference the factor here is not so much the image source data but the way it's displayed. ACR preview display must render none 1to1 scaled image (ie bigger or smaller than 100%) differently to pshop.

    As for finding whether this is the case, how it renders the image and how to change it I don't know and wouldn't have any clue where to start so cannot help you on that myself. For want of avoiding sounding like a smart arse (I really don't mean to ) the easiest way I can see is only trust 100% scale viewing when it comes to judging that factor of your images if you cannot resolve through higher res/monitor factors.

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