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  • help - compression problem

    I am using photoshop 6.0 and my camera outputs roughly a 2 mg jpg file at a size of 2560 x 1920 based on the settings I use in my camera. Picture quality is set at fine (highest)

    When I open up a picture in photoshop generally all I need to do is a levels adjustment and I adjust contrast in that screen as well.

    Once that is done I am prompted to save the file with the new adjustments. I do that and then when I look at the size of the file it is only 450 kb after the save.

    I am not changing image size at all.

    I know their must be a setting that adjusts the amount of compression when saving a jpg. file, and the compression is probably set to high. But I cannot find where to adjust this setting.

    Could someone please help me on this one?

    Thanks - Carl

  • #2
    Don't you get a little box that comes up when saving it, that is titled JPEG Opions? If so there is a slider that you move to the furthest point to the right to set the least amount of compression. If I were you I would choose "save as" then select the jpg format and the box should come up when you hit save. Hope that helps. It could be that somewhere down the line you saved something in a low res jpg format and that setting stays the same until you readjust it. Let me know if that helps.


    • #3
      I tried to duplicate what your doing, by opening a similiar type 2.3 Meg jpg file from digital camera, then after making level adjustments I selected file save and it saved back as 2.3 meg jpg. Are you going to file then save?

      When I use the jpg option in my digital camera I open the file in Photoshop, then save as a tif file. This allows me to open and close the file without any more loss than that I got from the camera to the first opening of the file.


      • #4
        Saving as a Tif would have been my first recommendation since it's a much better way to save a photo file. But I thought you chose to save as JPG for some reason and went on that.

        Yes, I do go to File > Save As.....etc


        • #5

          I meant to address that reply to Cendres, sorry I was not clear.

          I could not duplicate what was happening to him, just was wondering if he used File then Save?

          Yes I get them over to TIF just as soon as I can.


          • #6
            Forget my previous post. A slight confusion there.

            I didn't even see your name in the reply so I just thought you were Carl answering my last post. Guess we both got a little surprise there. Teach me not to pay more attention.

            OH well, the moral of the story here is save as a Tif and forget the Jpg.


            • #7
              Carl, Thats normal for PS to do that. I have some JPEG digital photos stored which are 3.99 mb when open, when stored are below 1 mb. There is no deterioration of image quality, and is simply the compression scheme PS utilizes, but, its best to save as TIF. I only keep some as JPEG because a couple of programs I use will only operate with JPEG format stuff. Tom


              • #8
                Hey Everyone,

                Sorry it has taken me so long to reply, we had a hockey game to go to today.

                First let me reconfirm a couple things on how I work with the files in general.

                #1) I take the images from my camera and put them into a folder on my hard drive. If I explore and find the image, it tells me it is roughly 2 mg.

                #2) I then open photoshop, do a file open and browse to the image and open it. At this point it is still a jpg file, not a PSD. I do the quick and dirty levels/contrast adjustment. Once that is done, I hit file save. There is not any windows that come up at all, it just closes the image window.

                #3 If I do a file save as then of course I have the option to save it in various formats including tiff. I generally do not do this because than I would essentially duplicate the file. There is no slider to adjust jpeg compression in this window.

                #4 Remember I am using Photoshop 6.0 I would be curious to know if DJ, George and Thomas George are using that version or an older version.

                I did find one area where I can adjust jpeg compression, In PS 6.0 if you go to file - save for web. A box opens up and there is a area that you can adjust compression. I did not have time to play around with it (and still haven't) but maybe that is the problem. I just don't understand why they would bury JPEG compression settings there and not in the preferences portion.

                Thomas, maybe you are right and thats just the way photoshop saves jpeg files, but it would seem odd that it would lose such a large portion of the file size without me reducing the actual size of the image.

                I used to use Paint Shop Pro and when you did a file save, there was a setting to adjust the amount of compression. If you did not change that setting, it would just default to your last setting you had made.

                I fully recognize that tiff is the way to go, but I only have 2 gb left out of 15 and my camera would make each of these pictures 15 mb each. I take a ton of pictures, but only print less than 10% if that, so I really would like to keep them in JPEG if possible.

                Thanks to everyone for taking the time to read this long followup. If you do have PS 6 I would be curious if you can find out something I havent yet. I will work on this tomorrow and will get back to everyone to see if I can figure anything else out.



                • #9
                  First of all, I am running Photoshop 6 same as you. I tried to duplicate your problem but my file size remained the same. I did however notice that the JPEG Options dialog box did not come up when I chose File > Save. It just saved it. However when I saved it going File > Save As, I did get the dialog box. If you don't want the image to be duplicated doing it this way then all you have to do is leave the file name the same and it will ask you if you want to replace it. Hit yes and the JPEG dialog box comes up. However, for safety sake I wouldn't do that until you see that it doesn't affect your only copy. If by creating a duplicate file you see that they are the same size then try over writing the file.

                  Since I did not get the same compression results you did, I can't say that this will be a fix for you. If I were you I would consult Adobe on the subject or if you belong to NAPP there is a great help desk on their website with quick answers to your problem. Something doesn't sound right. Good luck and don't forget to let us know what you find out.

                  Just a note here from experience, it is a good idea to have another copy of those files besides on your hard drive. Hope you back them up. I got caught a few times and that don't feel good.


                  • #10
                    I reread Toms post and I realized what you were probably refering to. That same photo I opened as a JPEG was a file size in Photoshop of 3.2MB but when I view it in Windows Explore it is only 981KB. Is that what you're refering to? If so that is normal. If I open that same file Photoshop will still say it is 3.2MB. I never quite understood that but it is normal as Tom says. Maybe someone can explain why that is exactly.


                    • #11
                      I really hope someone can explain that because it's something that's bugged me for ages. When you're trying to get an image down to a certain size, the only way you can check its real size is by looking it up on Windows Explorer!

                      In which case it doesn't matter if it's a JPEG, TIFF, PSD or whatever. PhotoShop seems to do that with all file formats.


                      • #12
                        No data is lost, just compressed by the software, a crude example would be folding a handkerchief to store it in a drawer. The folded one takes up less space but is all there and when opened, assumes its original dimensions. Dont be alarmed by this behavior of the program...its purpose is to allow more efficent storage of data thus not cloging up your hard drive with stuff so quickly. In answer to you question, I am running PS 6 as well as a few others. Good luck, Tom


                        • #13

                          I retested today, using Windows XP and Photoshop 6.01, and a test image of 2.3 Megs which I had downloaded to my hard drive directly out of my digital camera.

                          When I went to open the file in Photoshop I left clicked on the file, and it opened a small image at the bottom of the open file window and listed the file size as 2.3 Megs.

                          When I opened it in photoshop, the file size was 14 megs.

                          I made corrections with levels and then saved. I then closed the file, went to file open, left clicked on the file and it again listed the file size at the bottom of the file open window as 2.3 Megs. This is the normal compression used by Photoshop to save a jpg file. If you want more or less compression then you would select the save as feature and the use the jpg box to make the selection for compression.

                          If you open a jpg file that is 2 Megs when you left click it in the file open window, then in Photoshop the file should be 12 - 14 megs. If this file is then saved it would again be a 2 Meg file.

                          If the file is 2 Megs when opened in Photoshop, then when saved it will be compressed and be much smaller.

                          Look at your file by left clicking on it in the file open window and you will see the actual compressed size of the file. Then open it in Photoshop, make corrections, see what size it is when opened in Photoshop. Save and then recheck by closing the file, then going to file open, left click on the image file and see the file size at the bottom of the window, it should be very close to the same size you viewed earlier before opening in Photoshop.


                          • #14
                            I think I have it figured out now.

                            After experimenting a bit this morning utilizing DJ's post, I opened a file and did a levels adjustment. I then did a save as and then checked "a copy". I then selected the main save button and a window popped up. I was able to access the compression settings, It was set at a mid compression setting. I adjusted it to high compression (12) and saved the file. I then went into windows explorer and looked at the file size. It actually grew the file size from the original 2.1 mg to 4.5 mg.

                            Just to make sure, I then took another picture, did a levels adjustment and this time rather than doing a "save as" I only did file- save. Went back to explorer, checked the file size of this new image, and yes indeed that grew as well.

                            What I think this tells me is this, like paint shop pro, photoshop uses the last compression setting that was previously made. You may ask why did the file size actually grow? The reason I think, is that my camera comes up with its own internal compression ratio based on the internal setting that was selected (ie fine or good). The cameras internal setting compresses the image to roughly 2 mg at the image size I selected. If I shot at TIFF right out of the camera it would be almost 15 mgs.

                            I think photoshops least compressed setting actually is a little less compression than my camera does, therfor, that is why the file setting increased. It kind of makes sense now after I went into Paint Shop Pro because the only area you can actually change the compression setting is when you do a file -save as. Again that works the same, whatever you last set it at, that is the level for all new saves until you go in and change it to something else. Paint Shop Pro uses a % figure to represent compression and the default setting is 15% (The lower the %, the lower the compression).

                            One thing I am curious about is Georges post, which said he got the exact same file size (2.3 mg) after making a levels adjustment. George if you could do this, I would be real curious as to what your settings say. Open any image, do a file -save as. Check "save as copy" then hit save. As soon as you do that, a window will open up that says JPEG options, can you let me know what number it says (1-12). I am assuming you have 6.0.

                            Thomas, I still think you are correct in stating photoshop uses its own compression scheme to minimize file size while keeping the best image possible, but I do think it definitely increases or decreases the amount of compression based on what it has been set at.

                            Well sorry again for such a long post, but I wanted to share with you what I found out. I would of course welcome any additional comments or observations. I do appreciate everyones help. - Carl


                            • #15

                              To see the compressed size of a jpg image, when using Photoshop, go to file open and left click on the image you are interested in. The size of the compressed file, before being opened in Photoshop is shown at the bottom of the window.

                              I use this to see what size any file I am going to open in Photoshop is, before opening. In most cases since I use tif the size here and when opened in Photoshop is the same.

                              When I am going to sent a file over the Internet, I use the file save as feature and set the compression. I then check the file using open and left click to determine it's actual size.


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