Rotating pictures 90 degrees

Discussion in 'Photography Beginners' Forum' started by Peniole, May 16, 2007.

  1. Peniole

    Peniole TPF Noob!

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    Whatever programme I use to rotate pictures 90 degrees, and I'm talking JPEGs here, the resulting file always seems to be smaller (I mean bytes on disc here). Although I can't tell if there is any detriment to the image looking at it. About 10% loss in size.

    Any way of avoiding this? (other than using viewing programmes that use the EXIF data to just rotate the thumbnails). Or if this is even something to worry about?

    Photoshop seems to incurr the least loss but it throws away the EXIF data, and I can't seem to find where to stop it from doing that. I have for now PS 5.5 (it's free from my lab, and it works for my purposes so far). Other things I've noticed when you look at the file properties in windows, line resolution for horizontal and vertical was 312x312 dpi and now is 72x72dpi? Bit depth is retained at 24. Colour space data is no longer showing sRGB.

    Thanks in advance.
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The problem is that by rotating the image, you are opening and saving it again. The problem with that, is that JPEG is a compression format. So every time you open and then save a JPEG image, you are compressing it again.
     
  3. Peniole

    Peniole TPF Noob!

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    I see, so regardless of the manipulation you're doing, just by saving JPEGs you loose image data.

    Well I guess unless I'm shooting RAW, I should better always keep the original.

    Thanks Mike :thumbup:
     
  4. deadtoaster2

    deadtoaster2 TPF Noob!

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    Also, its best to rotate them in photoshop or some imaging program versus rotating them in windows or whatever OS you may be using. If you rotate them in the windows and fax viewer thing on win XP you will lose quite a deal of quality, whereas if you go into photoshop you retain most of the quality.
     
  5. xfloggingkylex

    xfloggingkylex TPF Noob!

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    the program I use for my image viewing and cropping is Fast Stones Image Viewer (freeware) and it features a lossless JPEG rotation in the browser. All you do is select the thumbnail(s) you want to rotate and right click, go to "JPEG Lossless Rotation" and select how much. Easy as that!
     
  6. Garbz

    Garbz No longer a newbie, moving up!

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    Also check your JPEG compression settings. "Normal" compression on my D200 equals 11/12 in Photoshop. I haven't checked exactly what "Fine" does, but I can't see a visible difference in the final pictures anyway.
     
  7. Peniole

    Peniole TPF Noob!

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    Thanks for the replies, I'll definitely check that freeware. I've been doing the rotation in PS and stil losing image data. I'm assuming that the SHQ setting in my olympus (1:2.7 compression I think) has even less compression than the 12 setting in PS.

    EDIT: Ok downloaded and tried the fast stone image viewer, lost even more than PS even with their lossless rotation. I gues it's ust the low JPEG compresion that the camera uses.
     
  8. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    I'm not certain...but there may be other factors involved in the file size than just the JPEG compression. What I'm saying is that just because the file size changes, doesn't necessarily mean that the image is being compresses more or less.

    If this is something that concerns you, then why not use a lossless format like TIFF or PSD?
     
  9. Peniole

    Peniole TPF Noob!

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    I agree, a lossless format is the way to go. I don't use them for all my shots for space concerns, I guess there's going to be a compromise somewhere.
     

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