06-26-2007, 11:23 PM
> For graphics LZW might not be appropriate, a scanned photo will not compress, and may even get larger (and slower).
Not true. In the hundreds of thousands of lzw tif files that I have worked with over the years, I have never seen an image get larger due to lzw compression. An image *might* not get significantly smaller using lzw compression, but in all likelihood it will.
In fact, given the growing dimensions of digital photographs, I've seen lzw compression rates increase significantly over the years as the growing amount of image data increases the likelihood of repetitive strings within the file.
You may be thinking of another compression technique -- perhaps Stuffit compression. When various compression programs lack the appropriate compression algorithm to deal with a particular kind of file they often generate larger output files than the original file alone would account for. Stuffit, in particular, is notable for doing that with audio files and some kinds of graphics.
Also, any slowdown due to using lzw vs uncompressed tif images is probably undetectable on any Mac made in this century.
OTOH, it did add almost a second's delay when I opened such images in Studio/8 on my Mac II, so I recommend that you do some testing to see which method is most efficient if your primary Mac is more than 20 years old.
Not true. In the hundreds of thousands of lzw tif files that I have worked with over the years, I have never seen an image get larger due to lzw compression. An image *might* not get significantly smaller using lzw compression, but in all likelihood it will.
In fact, given the growing dimensions of digital photographs, I've seen lzw compression rates increase significantly over the years as the growing amount of image data increases the likelihood of repetitive strings within the file.
You may be thinking of another compression technique -- perhaps Stuffit compression. When various compression programs lack the appropriate compression algorithm to deal with a particular kind of file they often generate larger output files than the original file alone would account for. Stuffit, in particular, is notable for doing that with audio files and some kinds of graphics.
Also, any slowdown due to using lzw vs uncompressed tif images is probably undetectable on any Mac made in this century.
OTOH, it did add almost a second's delay when I opened such images in Studio/8 on my Mac II, so I recommend that you do some testing to see which method is most efficient if your primary Mac is more than 20 years old.