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Decreasing file size of jpg photo
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Decreasing file size of jpg photo |
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Stephanos
since 2000-07-31
Posts 3618Statesboro, GA, USA 
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I just bought a scanner and it works great. I wanted to upload a jpg picture of myself to accompany my posts. However I read that the file needs to be no bigger than 5kb. I cannot seem to get one (100pixels X 150pixels) to save less than 16KB. I have an iMac and use Adobe Photodeluxe... and I have some other photo applications which I haven't learned yet. I thought maybe some of you might know how to do this. I use Mac OS, but I know alot of things work about the same cross platform. Any advice?? thanks, Stephen.  |
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Christopher
Moderator
Member Rara Avis
since 1999-08-02
Posts 8296Purgatorial Incarceration |
Hello Stephen, I don't know that much about Mac stuff, or the program... If you have the option (which I would guess you do) to export a file to a jpg format, you should also have a few options with it. Among these options should be things like a progressive factor. The lower the number, the smaller the file size. Quality factors are also often an option. (IE: Adobe Photoshop - High, Medium and Low qualities, which transfer into Large, Medium and Small files.) There may or may not be other options available to you that are relatively simple to use. Consulting your manual might be helpful... or buying a PC.  And if none of this is helpful, feel free to send me the picture (christopher@countlesshorizons.com) and I'll set it up for you. Peace, Christopher [This message has been edited by Christopher (edited 01-03-2001).] |
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Nan
Administrator
Member Seraphic
since 1999-05-20
Posts 21191Cape Cod Massachusetts USA |
...or upload it and we can fix it for you before it's approved for posting...  |
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doreen peri Member Elite
since 1999-05-25
Posts 3812Virginia |
Nan, you can't upload it unless it's 5K or less. the system won't let you....i'm having the same problem and it's baffling the heck out of me because i resize photo and art files on a daily basis for work. i have a new one i wanted to put up, too, and can't get it compressed to 5K. i use photoshop and saved it at 100x150 pixels and the smallest i could get it was 16K. and it's not a mac thing, though i do use mac.... i didn't know there was any application more powerful than photoshop for resizing and compression but if there is some application out there which is better capable of .jpg file compression, i'd like to know about it..... thanks all.. |
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Stephanos
since 2000-07-31
Posts 3618Statesboro, GA, USA |
Thanks Doreen Peri, I thought I was the only one. I tried to decrease the image quality to decrease file size, and I also had the lowest resolution setting (I think) that my program photodeluxe offered. Still 16K is the lowest for me. There may yet be some program options I am not aware of since this is all new to me. I will keep trying to fix it. To the administrators: Is there anyway to increase the system's minimum upload size? To doreen peri: If you figure out a solution, please e-mail me and let me know. thanks all (though still confused here) |
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Christopher
Moderator
Member Rara Avis
since 1999-08-02
Posts 8296Purgatorial Incarceration |
Hey y'all - while I like Photoshop (I use it at work), my program of preference is still the Corel package. For resizing, you can see how large the file is going to be, and affect it directly from the dialog box before you save it. (PhotoPaint specifically.) Please, Doreen and Stephen - send them to me and I'll fix them up by tonight.  Chris |
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Ron
Administrator
Member Rara Avis
since 1999-05-19
Posts 8669Michigan, US |
Don't be too quick to blame the software, guys. File compression, overly simplified, is based on finding binary similarities within the file. Got a big, 4K blue sky in your image? Instead of saving a byte for every sky pixel, I'll just say that "blue sky" is now called xyz and save the file with a 4096xyz tag - saving almost 4K. When the file is loaded by a program that understands the compression, the 4096xyz tag will be converted back to a nice pretty blue sky before being displayed on screen. Some images, however, just don't have a whole lot of binary similarities and can be a nightmare to compress below a certain point. The algorithm is looking for groups it can replace with smaller definitions; in our blue sky example, we have to have a definition (saying xyz=0000ff, for example) and a declaration (our 4096xyz). Altogether, we might say it takes 16 bytes to define and declare our 4K blue sky. A big savings! But what if the largest group of similarities in your images is a string of 20 red pixels? Well, we only saved 4 bytes. Ouch. So a "busy" image, with a lot of switches from one color to another, just isn't going to compress very well. And, ironically, that is more likely to happen with a smaller photo or a low resolution. Sometimes, the only solution is to find another, more amenable image. And, yes, Stephanos, I "could" raise the upload limit above 5K. But if your 16K photo is one of those that simply cannot be further compressed, that 16K is going to eventually be multiplied by every originating post you make, and then again by every person who views it. Opening a thread and waiting for a 5K photo (and most are actually 2-3K) takes a little more time than one with no picture, but only a little. And it's worth it to be able to "see" the person face-to-face. But larger images costs our Members more time, and Ceres more workload, and become less and less worth it. The 5K limit was a compromise that seems to work "most" of the time. Now, would anyone like to know why jpg (unlike gif and zip) is considered a "lossy" compression scheme?  |
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Nan
Administrator
Member Seraphic
since 1999-05-20
Posts 21191Cape Cod Massachusetts USA |
I think "scheme" is the keyword here... It's all a scheme to make our lives more complicated... and more lossy... |
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Stephanos
since 2000-07-31
Posts 3618Statesboro, GA, USA |
Hey guys.... I've figured it out! ...everything about jpeg compression?? No... but I can atleast compress my jpeg to 5K now. I downloaded a shareware program called "GraphicConverter" just to see if it worked any better for me. When I went to save the jpeg it gave the option to save "internet ready- without a resource fork". When I did this the file size ended up being several KBs smaller with pretty good picture quality. To the best of my limited understanding a resource fork is something that attaches the jpeg to it's creator application... You technical gurus (Ron for example ... your entry was fascinating but leaped a mile over my hurting skull) please let me know if that is wrong. Anyway thanks for all the comments. Now I am satisfied... atleast until someone knowlegeable comes along and tells me all the reasons why I can't do that. Stephen. |
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