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Image size reduction


Jeber

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This is only a tough question because I don't know how to do it. That and it doesn't really fit in any other catagory.I have an image that is currently 25kb, and I want to reduce the file size to less than 20k. Could somebody recommend a program to do this (Windows or Linux) and tell me how to go about it. I have access to Ifanview, Adobe Photoshop, Gimp and a couple of others. Any suggestions would be appreciated.

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IrfanView should do the trick. Sometimes you can crop the image enough to reduce file size. You can change the dimensions to reduce file size and retain quality or you can resample the image and maybe sacrifice a little quality. If it's a Windows Bitmap (.bmp) file you can simply save as a .jpg file and reduce file size a ton.If you want, you can send it to me as an attachment to an email and I'll play around with it. Then I'll tell you what I did for the best result.

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It depends a lot on what filetype you are using. Adobe Photoshop, no doubt, will give you the options to handle this.GIFGIFs support a maximum of 256 colors, but the number of colors can be reduced to lower the size of the image (GIFs are very common for webpages, therefore, optimized GIF's will load much more quickly). Try reducing the number of colors in a GIF to the lowest number needed (eg.: don't make a 2 color gif use 256 colors, it will be much larger than it needs to be)JPEGJPEGs are also popular for the web. They also make a great format for finalizing photos. The trick is to find the balance between quality and filesize. The answer is compression: the more you compress it, the smaller the filesize will be, but the lower the quality will be (you'll have a lot of messy, blurred egdes). But the less you compress it, the higher the quality will be, but the larger the filesize will be. JPEGs support 16-bit color (something in the millions -- a lot more than GIFs)TIFFTIFFs are not used for the web, because of their nature of being larger files. This is because they support 16, 24, and 32 bit color, but do not use a lossy compression algorithm like JPEGs do. They can be compressed, but use the LZW algorithm, which, again, is not lossy.PNGAn PNG image (pronounced "ping") is like the future GIF -- but it supports 24-bit color, and uses a much better compression algorithm than JPEG. However, PNGs are still somewhat larger files, as far as filesize goes.BMPDon't even bother. A Windows Bitmap is freakin' huge, no matter what the file's contents are. No compression, no optimization, no nothing.Is your image in a format I didn't list here?

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you can play around with quality setting on JPG files inside any photo program. if you increase JPG compression, file size is a lot smaller, but you start getting 'artifacts' (multi-colored blobs / smudges).

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OK, I think that worked. It's only a temporary change, but I did want to stay within forum guidlines on avatar size. Thanks for the help. Now I know something new. :rolleyes:

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Hmmm...I think you could get better quality using a GIF format, but you'll have to optimize it, depending on what program you use. It may preselect certain color usage for you, so it's better to do it manually.

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Ah, wait a second. I see your problem. The size you've specified for Avatar is making it strecth ;0The size you need to specify in your forum Avatar settings is 90 x 68 px

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The following is NOT related to avatar resizing but to compressing images!The latest bad boy in town is the JPEG2000 image compression (*.jp2 or *.j2k extensions)!Most newer image applications are able to handle the JPEG2000 format!But I am not sure if it is taking off as expected and have not seen anyone using it yet (self excluded)!Although I am not aware of the full details of this algorithm: Limited tests that I have ran with JPEG2000 (re: jpeg) appears to provide a 2-to-1 reduction in file size with equal resolution! Even IrfanView has this format built in!

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The following is NOT related to avatar resizing but to compressing images!The latest bad boy in town is the JPEG2000 image compression (*.jp2 or *.j2k extensions)!Most newer image applications are able to handle the JPEG2000 format!But I am not sure if it is taking off as expected and have not seen anyone using it yet (self excluded)!Although I am not aware of the full details of this algorithm:  Limited tests that I have ran with JPEG2000 (re: jpeg) appears to provide a 2-to-1 reduction in file size with equal resolution!  Even IrfanView has this format built in!
ok, stop your mind-reading, Randombox. how did you know i was just about to post a question "what is this new JPEG2000 i see in PSP8?" :) question though: do all current web browsers support Jpeg2000? as for my favorite standard, i use PNG to keep originals high-quality scans or original web images (it stores 'hotspots' and text can be re-edited in the future, and supports layering) and for general photos and all web pictures, i use Jpg (usually 10 to 15% compression). but now i'm interested in this new .jpeg2000 stuff. it would be great to make web image photo galleries that much smaller.
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Speaking of PNGs, when I view them in, say MS PhotoEditor or Windows Picture and Fax Viewer, they appear as do GIFs with a transparent background, however, when I use one of them in a web page, they appear with the default grey color.Anyone understand this and have experience working w/ PNGs?

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bruce,Out of curiosity i googled on >png transparency< and found the following excerpt here.

There's a petition (at PetitionOnline) for proper PNG support in IE for Windows. I am aware that MSIE 5.5+ for Windows supports an "AlphaImageLoader" filter that can be used to display PNG images with transparency. Personally, I don't consider it to be an acceptable replacement for standard PNG support, though it does mostly work, with some caveats (requires the site author to modify each web page; requires scripting to be turned on; requires extra documents to be loaded from the server; prevents visitors from easily saving the image to disk; slows down processing of non-transparent images; seems to fail once in a while for no apparent reason).
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Nudging Prelude76 :lol: Sometimes good ideas don't take off or get muddied up! I hope jpeg2000 does not become one of them but I see the writing on the wall! Every one comes up with their own image standards but most don't last! So, I think you have your homework cut out for you Prelude76! Give us the lo-down on jpeg2000 after you finish your term paper!

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