Re: [Gimp-user] optimizing image for internet using GiMP
What would happen to a jpeg image if I open it up and save it at 75% quality. Reopen the image and save it again at 75%? Would there be loss to quality? Seems like it would. Once I opened a picture I saved at 75% before and saved it at 100%. The file size increased. I don't understand that. There are times when I want to open a jpeg just to resize the picture, and then save it again - but I don't want to lose any more quality - and I don't want to increase the file size compared to what it was before. How do I go about handeling this? Also, where can I find documentation on the web where I can lern all about jpeg? Thanks in advance. On Wednesday 04 April 2001 19:13, you wrote: Rupert - An indexed image can contain any number of colors (3, 7, 21, 86, . . .) up to the maximum limit of 256. In brief: GIF is a simple indexed format, one byte per pixel, which limits the total number of colors to 256 maximum. It will allow for on/off transparency; one color can be called transparent. JPEG allows for millions of colors (3 bytes per pixel, actually, one each for Red, Green, and Blue), but its compression scheme is lossy, trading fine color detail for reduced size. The usual rule of thumb is GIF for line art and pictures with large areas of a constant color, JPEG for images with lots of detail such as photographs. Nothing really beats loading an image into the Gimp and just playing with it. There's always new stuff to be discovered. -- Rick Rosinski http://rickrosinski.com [EMAIL PROTECTED] ___ Gimp-user mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
Re: [Gimp-user] optimizing image for internet using GiMP
Hi Rick - Can't answer most of your questions, but I do have one suggestion. When dealing with existing jpegs, or graphics that you work with in Gimp and then convert to jpegs, save a "master" copy (as RGB) in .xcf, Gimp's native format. This way you preserve all of the original quality. Then if if you have to make any additional changes, you can go back to your "master" copy and work with it. ... of course, I use Gimp at work where I've got enough memory to store two of everything ;-) Teri Ward Seattle What would happen to a jpeg image if I open it up and save it at 75% quality. Reopen the image and save it again at 75%? Would there be loss to quality? Seems like it would. Once I opened a picture I saved at 75% before and saved it at 100%. The file size increased. I don't understand that. There are times when I want to open a jpeg just to resize the picture, and then save it again - but I don't want to lose any more quality - and I don't want to increase the file size compared to what it was before. How do I go about handeling this? Also, where can I find documentation on the web where I can lern all about jpeg? Thanks in advance. ___ Gimp-user mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
Re: [Gimp-user] optimizing image for internet using GiMP
On 03 Apr 2001 21:53:18 -0700, Jeff Trefftzs wrote: You can reduce the image size with Image-Scale Image; you can reduce the number of colors with Image-Mode-Indexed, which allows you to set the number of colors (up to 256, I believe), specify dithering, etc. Or, you can save the image as a jpeg, where you can set the compression level and thus reduce the number of pixels needed to represent the image. Thanks for your reply, Jeff. When changing the image to indexed, can one set any number of colours to the image (eg 32, 33, 34, 35, 36, etc) or does one have to stick to "computer numbers" such as 16, 32, 64, 128, etc? I must learn more about the the GIF and JPEG formatsthe I don't know WHAT I'm doing with the options given me in gimp! -- regs rupert ___ Gimp-user mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-user
