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JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE?? - Adobe Photoshop 7, CS, CS2 & CS3

Hi there, last day a friend shared me a trick with file size saving formats that he was keeping it secret cause he was very happy with it :) He teached me how to save my files in Jpeg for sending via email. He was having big file sizes like 50 mb converted in jpeg AND being amazingly transformed into 200 kb approx. When u save ur image, he told me to put the image quality to 0, again i was shocked. The most shocking is when u open it back (the jpg file) in PS7, the file size is ...

  1. #1

    Default JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Hi there,
    last day a friend shared me a trick with file size saving formats that he was keeping it secret cause he was very happy with it :)

    He teached me how to save my files in Jpeg for sending via email.
    He was having big file sizes like 50 mb converted in jpeg AND being amazingly transformed into 200 kb approx.

    When u save ur image, he told me to put the image quality to 0, again i was shocked.
    The most shocking is when u open it back (the jpg file) in PS7, the file size is the SAME as the 50 mb file, No Pixels or else and u can print it normally !!!!

    All this operation was done on MAC.
    I came to try it on my Pc, the file size result was the same but the jpg image was pixelised in PS7, but the pixel dimension r the same, but showing pixelised .

    WHO CAN EXPLAIN ME THIS AMAZING THINK ??

    THX ALOT IN ADVANCE

    HAVE A NICE DAY !
    SARO_AJEMIAN@adobeforums.com Guest

  2. #2

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    IF you are saving with compression (jpeg) you do lose quality, Theres no difference in Jpegs on PC and Mac, not that I know of any way. You are probably zooming into the image on the PC is the only thing I can think of.
    Peace_Pipe@adobeforums.com Guest

  3. #3

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    HELLO Peace Pipe

    well no actually im not zooming in, i saw them on actual pixels, both of them, Mac and Pc.

    What i would like to know is how does the file go smaller and recover in its original file size in PS7 without loosing anything, IN A WAY LIKE ZIP FILES. !!

    SEE IT, TRY IT !
    SARO_AJEMIAN@adobeforums.com Guest

  4. #4

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Saro,

    What you see in the Options Bar in Photoshop (the 50 MB) is the fileīs _memory size_ (the files uncompressed size) not itīs physical size. Yes, a JPEG compression is not much different in effect than a ZIP file. Both are methods for compression, although JPEG is lossy as hell, ZIP is not.

    Mathias
    Mathias_Vejerslev@adobeforums.com Guest

  5. #5

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Maybe;

    was the JPEG2 / JPEG 2000 file format used ?.
    hot_denim@adobeforums.com Guest

  6. #6

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    SARO,

    What are the pixel dimensions?

    How many layers? Keep in mind that you can easily make a 50 MB PSD that would save to a 200K JPG. Or as Mathias pointed out you may be comparing the working size in memory to the output size.

    There are no secret formulas for JPG output. The way to get the smallest files in Photoshop is to use "Save For Web" to get the raw pixel data without the extra image information.
    Photo_Help@adobeforums.com Guest

  7. #7

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    You threw out almost all the image quality.

    So what?
    Chris_Cox@adobeforums.com Guest

  8. #8

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    HI AGAIN ,

    OK here is an example that i made:

    I have a file 7559 x 1831 pixels WITH 10 LAYERS >> Doc:52.8M/72.3M

    saved it >> Save as "test copy.jpg" use lower case extension [checked] JPEG Options >> matte>none - Quality>0 - Format Options>Progressive Scans 3

    RESULT:
    I HAD A FILE Dimensions 7559 x 1831 File Size >>2M58 !!!

    WHEN I OPEN BACK IN PS.7 IT GIVES ME A Doc:52.8M/52.8M !!!
    image size resolution is 300 so u can PRINT IT NORMALLY !!!

    WAS MY EXPLANATION CLEAR ENOUGH ??
    SARO_AJEMIAN@adobeforums.com Guest

  9. #9

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    When you make a .jpg file the pixel dimension remain the same no matter what quality you select. So it is normal for a .jpg to open with the same pixel dimensions. The image will be seriously degraded in quality but the pixel dimensions will still be the same as the original.

    Yes, you have the same number of pixels in the file so you can print the .jpg at the same resolutions as the original .psd, the difference is that the .jpg will look really bad. Perhaps the confusion here is that one might think that the number of pixels determines the quality of the image. That is not the case.

    Gary
    Gary_Hummell@adobeforums.com Guest

  10. #10

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Saro,

    The way JPG compression works is by representing a section of a picture (Possibly several pixels) with one block of color that is an average of the pixels that were there. This block still takes up the same amount of pixels but it would be like making a tile mosaic with 4" tiles instead of 1" tiles. It is a lot easier to store the location of 9 tiles per foot instead of 144 tiles per foot but the mosaic won't look nearly as good.

    When photoshop opens the JPG again it must store the location of every Physical pixel again. The data is all uncompressed so your computer doesn't need to uncompress and recompress the image every time you make a change.

    Your friend is confused.
    Photo_Help@adobeforums.com Guest

  11. #11

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Hi Gary

    I talked with my friend, he has a big inkjet solvent based printer 2m30 large.

    A client sent him or uploaded some files for him that he could download them and print for him.
    The files were 46mb zipped and saved as jpg like i told u.
    They 8 big posters 2,50m by 1m.

    He printed them and no pixels or major problem !

    what do u say ? its not that bad .

    see u
    SARO_AJEMIAN@adobeforums.com Guest

  12. #12

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Saro,

    Then the compression is very low on the files your friend is using. What you described were highly overcomressed images.
    Photo_Help@adobeforums.com Guest

  13. #13

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Saro, you've now had this explained by some of the top notch people around here, and you keep arguing.

    OKAY, you win. You can compress, uncompress and print .jpegs with no loss. Super Cool! You refuse to listen to the scientific and proven situation regarding .jpeg compression, so go for it. When you print the one image that looks like crap because you lost the image quality and the fine details are blurry squares, remember what was told to you, and go "Oh, THAT's what they were talking about!"
    Ol__Whozit@adobeforums.com Guest

  14. #14

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??



    HAD A FILE Dimensions 7559 x 1831 File Size >>2M58 !!!





    WHEN I OPEN BACK IN PS.7 IT GIVES ME A Doc:52.8M/52.8M !!!




    This figure is the size of the photo as a uncompressed image. I.e as in memory. Eg. Like a grid of pixels each pixel takign 3 bytes space (1 for each R,G,B), also acount for alpha channels etc.... Also take into accoun number of layers.
    hot_denim@adobeforums.com Guest

  15. #15

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Is it possible that this guy cannot see the horrible JPEG artifacts created but such a high degree of JPEG compression?

    ....hmmm... I thought those were 8x8 pixel squares that Jpegs created...
    John_Slate@adobeforums.com Guest

  16. #16

    Default Re: JPEG convertions!! WHO CAN EXPLAIN ME HOW CAN IT BE??

    Hi ppl ,

    1st of all thx alot for ur explanations, they r all gr8.

    I must agree, i didnt see the printed banners myself ! It sounded illogical for me to lose the quality of an image and bring it back like that ! Thats why i posted this question here so i can be sure that , this is not a good technique to use .

    Anyway, Ol' Whozit im really sorry if i made u lose some precious time. I didnt ment to .

    Best regards

    ORAS
    SARO_AJEMIAN@adobeforums.com Guest

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