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I'm currently compiling an ebook which is comprised mainly of black and white images.
There are quite a few of them, so I really have to keep the file size to a minimum to stop the ebook becoming unwieldy.
However, the book's main use is for printing, so the images have to be 300dpi to come out OK.
The smallest file sizes I can get are with gif's as there is only 2 colours involved. But whenever I save as .gif, it changes to 72 dpi.
So my questions are:
1) Is there anyway to make a 300 dpi gif?
2) If not, will a gif respond OK to being made 300/72 times bigger and then resized back down to the required size to get the resolution?
Or am I going about it all wrong :-)
Thanks for any help you can give,
All the Best
Will this turn out nicely?
Your idea for creating a GIF with larger dimensions and then resizing the image works with a browser - but I have never worked with ebooks, so I can't say for sure that this is your answer.
> The smallest file sizes I can get are with gif's as there is only 2 colours involved.
Now this is a major factor. With only 2 colors, unless the image lines are all perfectly horizontal and vertical, I'd imagine you will get the jaggies no matter what.
Are your source files only 2 color? Even if they look like two color to the eye, I'd suggest saving at 8 colors.
It's nice to be in the same boat KingKelly - even if the one we're in is a bit leaky ;-)
Tedster - This is cool - you reckon a compressed TIFF might be the way to go. Excellent, I'll give it a try.
KingKelly - have you tried this with gif's? I'm not sure why you have to do this with a jpeg - can you not just make it the resolution you want?
Awaiting the next instalment with anticipation...
I have been using 8-colour gif's and they look OK on the screen. Hopefully tomorrow I'll get a chance to print and see whether the old 'make em big and shrink em' technique works OK.
TIF is a lossless image format... meaning it's bloody huge like BMPs. But, you can save TIFs in a compressed format (LZW compression I think) which saves some space.
JPG is a "lossy" image format, meaning the software saving the file discards image data it feels is unnecessary to the image. Every time you open and re-save a JPG you may be losing a little more of your image data, causing a long-term degradation in the quality of your file.
Which is why you should always keep a bloody huge "original" backup of any important images in a lossless format like TIF or BMP.
Your on the money. The artifacts generate more artifacts and pretty soon...eecccch!
We were talking about the Pegasus editor here a while ago. One of its excellent features is the ability to open a jpg and flip it, or rotate it, and even crop it - all without degrading the image.
It does this by moving the actual data directly in the file, rather than decompressing the image, manipulating, and then recompressing the image, artifacts and all.
This is a trick that Photoshop can't do (well, I haven't checked out v.7 yet) and one that it darned well should. Pegasus has saved me lots of time when clients send jpg scans of slides but have them oriented incorrectly.