changing without deteriorating original image

Discussion in 'Digital Cameras' started by Louise, Apr 2, 2005.

  1. Louise

    Louise Guest

    I have a Canon S400 and am shooting at the best settings, getting jpgs
    between 1500 and 2000kb per image.

    I want to edit these in Photoshop and keep the original as high quality
    as possible. As I understand it, this means that the first thing I
    should do is change them from jpg to tiff so that the image doesn't
    degrade with every edit.

    Which software would be best used to change the original jpg to a tiff:
    I have Photoshop, ACDsee, Breezebrowser and probably one or two others
    somewhere on my hard drive :)

    Then I have a tiff and I open it in Photoshop and I crop, adjust color,
    contrast, etc. as necessary. Then I save it as a tiff.

    At this point, have I lost quality?

    NOW - I want to save these images at a much smaller size so that I can
    put them on a web page.

    I see that Photoshop provides the option of "save for web" and it offers
    different levels of jpg compression for loading speed and that works
    fine and leaves me with an image that is about .

    But - I can't seem to make the images smaller and when they load on the
    web, they are large and pixelated. I tried making the tif images
    smaller: image size/document size, that that didn't seem to end up
    making the image size smaller when I changed it to jpg.

    I have the impression that I've got the right idea (at least I hope so),
    but that I'm doing something in the wrong order or something....

    Help and suggestions appreciated.

    TIA

    Louise
     
    Louise, Apr 2, 2005
    #1
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  2. Louise

    Ali Guest

    You need to specify the size of the image in pixels if the image is part
    of a web page, but if your link is direct to the image, then it should
    auto size under IE 5 or 6
    img src="typer/DPP_0477.jpg" height=640 width=427

    Remember to keep the aspect ratio, or it will stretch and skew the
    image.
     
    Ali, Apr 3, 2005
    #2
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  3. Louise

    Louise Guest

    Thanks. That will keep the sizing correct

    But is there also an optimal way to crop, sharpen, etc. before resizing
    or after?

    Louise
     
    Louise, Apr 3, 2005
    #3
  4. Louise

    Ken Weitzel Guest

    Hi...

    Just my two cents worth...

    Do all your tweaking before re-sizing. After re-sizing you might
    want a second sharpening.

    Ken
     
    Ken Weitzel, Apr 3, 2005
    #4
  5. Louise

    JPS Guest

    In message <>,
    .... or increase the contrast in a bright area; the JPEG artifacts will
    show up there, too, and you will get posterization as well.
    --
     
    JPS, Apr 3, 2005
    #5
  6. Louise

    JPS Guest

    In message <>,
    While we're on this subject, I just remembered that there was a reason
    why some images develop a 2:1 pixel aspect when you use the zoom tool in
    IE. Does anyone recall what causes that?
    --
     
    JPS, Apr 3, 2005
    #6
  7. : But is there also an optimal way to crop, sharpen, etc. before resizing
    : or after?

    In general I do all my editing on the largest (number of pixels) image
    possible. This way any slight inconsistancies in my editing (slight
    wobble to trim lines, etc) will become less noticeable after a resize. But
    if you do your editing after the resize, the slight inconsistancies remain
    noticable. The biggest disadvantage of doing the edits on huge images is
    processing time. Every process (cut, paste, apply filter, etc) takes
    longer. So you have to choose a happy medium between speed and image size,
    taking into account your particular combination of computer, memory size,
    image size, amount of "playing" you want to do, and patience.

    BTW, remember that when editing, the editing software rarely cares how big
    the print image will be. It only worrys about number of pixels. So if you
    do your editing on a 1200x1200 pixel image that will be printed as a
    600dpi image at 2" x 2" or at 100dpi image at 12" x 12", the editing
    process will be the same. Thus a 10 pixel wobble in an edit printed at
    100dpi will be 1/10" which is somewhat noticable while the same wobble
    printed at 600dpi would only be 1/60", totally invisible.

    So when you finish your edits, and change the print size, and resolution
    most inconsistancies in the edit would become invisible. This is why I
    do my edits at the highest resolution image I can, and many cuts are done
    at 300% on the screen to make any shaky hand movements less critical. Then
    when I am completely done, I resize and adjust resolution to match the
    desired finished product. Be sure to do a save of the image after the
    edits and before the resize. This way if the resized image is the wrong
    size or has pixelating, you can go back to the hi-res image to redo the
    resize. If you shrink an image and then expand it, pixelating will be the
    result. But if you do a seperate shrink from the original large edited
    image, pixelating will be reduced.

    One other point that was asked about is saving the work. I use Photoshop
    and so my comments will be from that point of view. When you load the
    original image from JPG the program converts it to the working format in
    memory. Any conversion errors will happen then. Then for the entire edit
    process I keep the image in that working format. Saving the backup images
    along the way will be in the Photoshop format and thus no loss will be
    made from conversion. Lastly, after the final resize, I save to the long
    term storage (JPG) which will be the second conversion. So you only end up
    with two sessions of conversion errors, which will be mostly
    unrecognizable to the eye. It is only when you make a conversion to JPG
    after each edit, and a reconversion back to the working format before
    doing the next edit that the cumulative conversion errors mount up to a
    noticable level.

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Apr 3, 2005
    #7
  8. Louise

    I may be dumb but I assume that you will do all your work on a COPY of the
    original so that you can always keep the original as high quality!

    Gerrit
     
    Gerrit 't Hart, Apr 3, 2005
    #8
  9. Louise

    paul Guest

    1. Archive the originals in a sub-folder & on CD or if you only plan to
    edit a few of the pictures, use that only for originals that get editing
    (take a lot of care not to mess up in this culling process).

    2. Edit in photoshop & save in PSD if you have adjustment layers and
    want to keep them or flatten & save as jpeg quality 11 if you don't plan
    to re-visit the editing. You can save as you go in jpeg and it won't
    damage the file until you close. At 11 there is no noticeable damage &
    files are much smaller than tif, at 12 you might as well save tif.

    3. Sharpen last if at all since your camera probably already applies
    sharpening. Create a subfolder for reduced web versions. Re-sharpen
    reduced web versions before save-as-web. Keep web files well under 100k
    for reasonable download at about 640 pixels on the long end (1024 if you
    really want it huge, 480 if small is OK). Save at 50%-70% quality
    depending on if it has broad transition areas like sky that might show
    banding. Zoom in at least 100% or more during the save process to
    observe the effect of jpeg compression as you move the slider.
    Sharpening halos & noise grain get exaggerated with compression, color
    depth decreases causing banding & posterizing & square artifacts appear
    in various sizes. 30k files would be nice if the image can stand that
    compression.

    4. Use Irfanview to batch the thumbnails at a low quality maybe 40% with
    additional sharpening; pretty strong, maybe 20. That's for the 100 pixel
    thumbs I do, if the thumbs are larger or pictures fewer, you might want
    to do them in photoshop at a better quality. I usually use irfanview to
    batch out the web versions also & only use PS if it's a bit tricky
    needing a different level of sharpening or I feel the series is
    especially deserving of more attention. It's a lot more work.
     
    paul, Apr 3, 2005
    #9
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