Lost Bytes with roatation in Windows Photo and Fax viewer

Discussion in 'Windows XP Photos' started by Scott092707, Apr 25, 2008.

  1. Scott092707

    Scott092707 Guest

    I wished to rotate .jpg photos so that in a slideshow people don't have to
    crane their necks constantly to view the pictures. I have found that after
    rotation, the picture size is reduced by 44 bytes (one example;don't know if
    it's consistant with each picture), and that the bytes don't come back if
    rotated back to the original orientation. Further 90-degree roation adds or
    removes an additional 5 bytes, but no more. Naturally, I want full
    resolution when I go to print the photos, in the original orientation, so I
    want to know:
    1) what causes the loss of the initial 44 bytes;
    2) what causes the additional loss/gain of 5 bytes;
    and
    3) whether those lost 44/5 bytes are unnecessary and I shouldn't worry about
    it,
    or I should never rotate pictures, or what?

    In case the info is necessary, I am using Windows XP-Pro Vers. 2002 SP 2

    Actual data: orig. photo 1.823 KB, rotated photo 1.779/1.774 KB

    -Scott
     
    Scott092707, Apr 25, 2008
    #1
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  2. Scott092707

    Yves Alarie Guest

    At 1,823 KB file size you have more bytes than you need a loss of 44 bytes
    is nothing.
    But really, this is not the way it works for printing, the file size
    obviously reflects how large a print you can get but the real numbers you
    want are the pixel dimensions.
    The "rule of thumb" is if you want a great print you divide the pixel
    dimensions by 300.
    At 1,823 KB file, I am guessing that the pixel dimensions will be something
    like 2048 x 1360. So you can get a print of 2048/300 = 6.8 inches by
    1360/300 = 4.5 inches. Now you can reduce 300 to around 200 and still get a
    very good print.
    Take a look at you file size in a particular photo folder. For a particular
    camera, the pixel dimensions will always be the same for all photos in the
    folder, but the file size will vary according to how much information you
    have in each image. The extremes would be taking a photo of a plain black
    and white object (photo # 1) and a landscape photo with lots of details and
    colors (photo #2). If you look at the size of the files, photo #1 would be
    very small while photo #2 would be very large. However, if you look at the
    pixel dimensions, they would be exactly the same for both photos.
    To find the pixel dimensions of your photos, just place your mouse pointer
    over a thumbnail or file name. A box will open and Dimensions will be the
    first item listed. Another way to get it is to use the Details view for your
    folder. Open the folder in Details view and right click on the Name column
    header, a list will open, click on More and then check Dimension to add this
    info as a column.
    The bottom line is: pixel dimensions control print quality, not file size.


    "Scott092707" <> wrote in message
    news:...
    >I wished to rotate .jpg photos so that in a slideshow people don't have to
    > crane their necks constantly to view the pictures. I have found that
    > after
    > rotation, the picture size is reduced by 44 bytes (one example;don't know
    > if
    > it's consistant with each picture), and that the bytes don't come back if
    > rotated back to the original orientation. Further 90-degree roation adds
    > or
    > removes an additional 5 bytes, but no more. Naturally, I want full
    > resolution when I go to print the photos, in the original orientation, so
    > I
    > want to know:
    > 1) what causes the loss of the initial 44 bytes;
    > 2) what causes the additional loss/gain of 5 bytes;
    > and
    > 3) whether those lost 44/5 bytes are unnecessary and I shouldn't worry
    > about
    > it,
    > or I should never rotate pictures, or what?
    >
    > In case the info is necessary, I am using Windows XP-Pro Vers. 2002 SP 2
    >
    > Actual data: orig. photo 1.823 KB, rotated photo 1.779/1.774 KB
    >
    > -Scott
     
    Yves Alarie, Apr 25, 2008
    #2
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  3. Scott092707

    Scott092707 Guest

    Re: Lost Bytes with rotatation in Windows Photo and Fax viewer

    Thank you, Yves.
    You have relieved me as to potential loss of quality in the print.
    And taught me an interesting rule-of-thumb.

    I am still curious, tho' :
    a)why the pixels initially disappear,
    b)why they do not subsequently do so,
    and c) why the size bounces back and forth by 5 bytes
    depending on the orientation.

    (I'm ALWAYS curious...)

    "Yves Alarie" wrote:

    > At 1,823 KB file size you have more bytes than you need a loss of 44 bytes
    > is nothing.
    > But really, this is not the way it works for printing, the file size
    > obviously reflects how large a print you can get but the real numbers you
    > want are the pixel dimensions.
    > The "rule of thumb" is if you want a great print you divide the pixel
    > dimensions by 300.
    > At 1,823 KB file, I am guessing that the pixel dimensions will be something
    > like 2048 x 1360. So you can get a print of 2048/300 = 6.8 inches by
    > 1360/300 = 4.5 inches. Now you can reduce 300 to around 200 and still get a
    > very good print.
    > Take a look at you file size in a particular photo folder. For a particular
    > camera, the pixel dimensions will always be the same for all photos in the
    > folder, but the file size will vary according to how much information you
    > have in each image. The extremes would be taking a photo of a plain black
    > and white object (photo # 1) and a landscape photo with lots of details and
    > colors (photo #2). If you look at the size of the files, photo #1 would be
    > very small while photo #2 would be very large. However, if you look at the
    > pixel dimensions, they would be exactly the same for both photos.
    > To find the pixel dimensions of your photos, just place your mouse pointer
    > over a thumbnail or file name. A box will open and Dimensions will be the
    > first item listed. Another way to get it is to use the Details view for your
    > folder. Open the folder in Details view and right click on the Name column
    > header, a list will open, click on More and then check Dimension to add this
    > info as a column.
    > The bottom line is: pixel dimensions control print quality, not file size.
    >
    >
     
    Scott092707, Apr 25, 2008
    #3
  4. Scott092707

    Yves Alarie Guest

    Re: Lost Bytes with rotatation in Windows Photo and Fax viewer

    If you open a photo file to view it and then close it without making any
    change, the size of the file will not change.

    However, if you make a change such as rotation, and you close the file the
    compression software on your computer is more efficient than the compression
    software in your camera and when "saving" the change the file size will be
    slightly smaller but there will be no loss in quality (the term used is
    lossless rotation).

    If you make other changes such as adding text, removing red eye, etc. and
    you save the file there will "some" loss in quality since the file will need
    to be compressed again to save it. However this loss in quality is not
    something you can detect. So no need to worry about it. It is best to make
    all your changes and then "save as" and give another name so you still keep
    the original file and best to do all your editing so you will do only one
    "save as", but don't worry about two or three editing of the same file.

    You can read a lot more details about JPG and how this compression work at
    this site:

    http://en.wikipedia.org/wiki/JPEG#Color_space_transformation
    "Scott092707" <> wrote in message
    news:...
    > Thank you, Yves.
    > You have relieved me as to potential loss of quality in the print.
    > And taught me an interesting rule-of-thumb.
    >
    > I am still curious, tho' :
    > a)why the pixels initially disappear,
    > b)why they do not subsequently do so,
    > and c) why the size bounces back and forth by 5 bytes
    > depending on the orientation.
    >
    > (I'm ALWAYS curious...)
    >
    > "Yves Alarie" wrote:
    >
    >> At 1,823 KB file size you have more bytes than you need a loss of 44
    >> bytes
    >> is nothing.
    >> But really, this is not the way it works for printing, the file size
    >> obviously reflects how large a print you can get but the real numbers
    >> you
    >> want are the pixel dimensions.
    >> The "rule of thumb" is if you want a great print you divide the pixel
    >> dimensions by 300.
    >> At 1,823 KB file, I am guessing that the pixel dimensions will be
    >> something
    >> like 2048 x 1360. So you can get a print of 2048/300 = 6.8 inches by
    >> 1360/300 = 4.5 inches. Now you can reduce 300 to around 200 and still get
    >> a
    >> very good print.
    >> Take a look at you file size in a particular photo folder. For a
    >> particular
    >> camera, the pixel dimensions will always be the same for all photos in
    >> the
    >> folder, but the file size will vary according to how much information you
    >> have in each image. The extremes would be taking a photo of a plain black
    >> and white object (photo # 1) and a landscape photo with lots of details
    >> and
    >> colors (photo #2). If you look at the size of the files, photo #1 would
    >> be
    >> very small while photo #2 would be very large. However, if you look at
    >> the
    >> pixel dimensions, they would be exactly the same for both photos.
    >> To find the pixel dimensions of your photos, just place your mouse
    >> pointer
    >> over a thumbnail or file name. A box will open and Dimensions will be the
    >> first item listed. Another way to get it is to use the Details view for
    >> your
    >> folder. Open the folder in Details view and right click on the Name
    >> column
    >> header, a list will open, click on More and then check Dimension to add
    >> this
    >> info as a column.
    >> The bottom line is: pixel dimensions control print quality, not file
    >> size.
    >>
    >>
     
    Yves Alarie, Apr 26, 2008
    #4
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