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Thread: Help!!! Resolution problem after RAW conversion

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    Teralee98's Avatar
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    Help!!! Resolution problem after RAW conversion

    I had my first shoot the other day and shot in CR2. I got home and put ALL images straight from the card onto disc, then put them into Digital Photo Professional. I selected all images and clicked Batch change and changed all images to jpeg and put them into a folder. This then changed the size of the image to a 6x9inch?? What am I doing wrong??? I have Photoshop CS2 I understand that changing from RAW to jpeg loses info but I didn't think it would lose info that drastically. The original Camera Raw image dimensions are 3456 x 2298 and is 7.2mb. Once changed and I 'get info' on the jpeg the dimensions are 2304 x 3456 and is 6mb (not THAT much of a change) Once in photoshop, the document size is 9.873 width 6.583 Height @ 300 resolution???? I've never had a problem with this before and have quite happily converted CR2 images to jpeg AND (even with the loss of info) come out with really nice photos.......I hope I'm not rambling but I'm really stuck! If you could help that would be GREATLY appreciated! Thankyou!

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    Moderator Dave Humphries's Avatar
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    Re: Help!!!

    Hi Teralee,

    Is there a problem?
    9.873 width x 300 = 2961px, so not vastly different.

    It isn't just that you have the unit of measure being displayed different from before is it?

    Or is the batch process taking the embedded jpg instead of making a new one?

    Sorry, I don't have CS2, or do batch processing, so I think I will stand back and wait for a better expert to reply.

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    Teralee98's Avatar
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    Re: Help!!! Resolution problem after RAW conversion

    Hi Dave Thanks for that I didn't think there was a prob either but if I crop the image to a size larger than 6x9in it stretches the image? it doesn't compact it like usual? (if you get what I mean )

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    Moderator Dave Humphries's Avatar
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    Re: Help!!! Resolution problem after RAW conversion

    To be honest, I have never understood working in inches or cm with digital images; I always work in pixels.
    You know where you are with them, they don't change if you tweak the dpi settings (or do I mean ppi).

    Maybe this is because I don't print often, but when I do, I just look at how many pixels it is, divide it by say 100 and think of that as the absolute maximum "inches" size I should print at, then find a bit of photo paper nearest that size, or smaller if I don't need it that big and I'm safe in the knowledge I have resolution 'in hand' and will get a higher quality print.

    That's how I work anyway, but that's not to say it is better.

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    Re: Help!!! Resolution problem after RAW conversion

    Hi Teralee,

    This is something that confuses a lot of people. Basically, "Image size" is a meaningless concept until the image is physically printed - until that point the ONLY thing that matters is the number of pixels across and down.

    I'll give you a couple of examples ...

    You have an image that is 2000 pixels high and 3000 pixels wide. If the image was set to a resolution of 1 pixel per inch then the image would print 2000 inches high and 3000 pixels wide. If the resolution was set to 100 pixels per inch then it would print 20.00 inches high and 30.00 inches wide - but - on your screen it's the same image regardless (still the same number of "dots").

    Does this help?

    Changing from RAW to JPEG may change the size of the file because JPEG chucks away a lot of info that it thinks isn't needed (and squishes what's let to make it even smaller), but the actual number of pixels shouldn't change unless you crop or resample the image.
    Last edited by Colin Southern; 24th September 2009 at 10:22 PM.

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    Teralee98's Avatar
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    Re: Help!!! Resolution problem after RAW conversion

    Thanks Colin your explanation was a great help! Yours too Dave, I'm going to keep up with what I was doing. I think I have been converted to pixels only now!!! (Damn document size!! ) Hope your having a great day\night Love the forums!! such an awesome help!!

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Teralee98 View Post
    Thanks Colin your explanation was a great help!
    No worries - glad I could help

    By the way, I lied (about image size not mattering) (kind of). It does have an effect when your adding text (as in names to frames etc) , but that's not anything to worry about at this stage.

    Unlike Dave, I tend to work more in resolutions - I tell my RAW converter to spit it out at 180 DPI (which is usually close to the size I print anyway) (I print BIG canvases) ... it's only when I'm displaying shots here that I typically then drop it down to "X" number of pixels.

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    Moderator Dave Humphries's Avatar
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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Teralee98 View Post
    The original Camera Raw image dimensions are 3456 x 2298 and is 7.2mb. Once changed and I 'get info' on the jpeg the dimensions are 2304 x 3456 and is 6mb (not THAT much of a change)
    I may be over analysing this, but looking at these figures, I am guessing the image was in portrait orientation and the conversion to jpg did the rotate and threw away the 6 pixels difference between 2304 (RAW height) and 2298 (jpg width). Because jpg has to be in 8 x 8 pixel blocks.
    Does 3456 divide into 8 to confirm the theory?

    The subsequent changes are another matter!

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Dave Humphries View Post
    Does 3456 divide into 8 to confirm the theory?
    Using my HP41cx app for my iPhone, I can confirm that it fits exactly 432 times

    Houston, we have a solution!

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    Re: Help!!! Resolution problem after RAW conversion

    I could be way off on this Teralee and I'm sure the pros will set me straight in short order but are you just looking at your monitor and staring at 6x9 photo? My understanding is that a monitors resolution is 72ppi. Try just changing the resolution to 72 and see if you don't get a lot bigger picture with seemingly the same picture quality. Just a thought.

    OK, back to the dungeon.

    Colin

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Colin O'Regan View Post
    My understanding is that a monitors resolution is 72ppi. Try just changing the resolution to 72
    Hi Colin,

    It's been the "resolution" of a "generic" monitor for many years - often it's in the ball park, but actual resolutions vary. Case-in-point, the screen I'm on right now has 1920 pixels and measures 20.5 inches across the horizontal - so that's 93.66 pixels per inch.

    I think that many don't seem to realise that normally there's not a 1 to 1 co-relation between the number of pixels in an image and the number of pixels used to display that image on any given monitor (it's only 1:1 when viewed at 100%), which is why sharpening looks way different on a monitor compared to a physical print.

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Colin Southern View Post
    You have an image that is 2000 pixels high and 3000 pixels wide... If the resolution was set to 1000 pixels per inch then it would print 20.00 inches high and 30.00 inches wide - but - on your screen it's the same image regardless (still the same number of "dots").
    Just to clarify, Colin, I guess you mean 2 inches high and 3 inches wide, correct?

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Alis View Post
    Just to clarify, Colin, I guess you mean 2 inches high and 3 inches wide, correct?
    or 100 ppi

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by Alis View Post
    Just to clarify, Colin, I guess you mean 2 inches high and 3 inches wide, correct?
    Doh - sorry - I must have hit one too many zeros by mistake. Well caught thanks. I've corrected the original error.

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    Re: Help!!! Resolution problem after RAW conversion

    Quote Originally Posted by wjh31 View Post
    or 100 ppi
    Yes, that's what I was meaning.

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