If I zip up a tif, is the compression lossless? i.e. when I unzip it, will it be exactly the same file as before?
Compressing TIFs
Miscellaneous Forums/General Discussion/Compressing TIFs Lol, yep. Unless the zip is corrupted.
you confuse image compression with file compression.
image compression is to reduce filesize permanently, file compression is reversible, temporary.
image compression is to reduce filesize permanently, file compression is reversible, temporary.
Not confused, just wanted to confirm. Which you've done. Thanks!
Asking if Zip is lossless indicates an incomprehension of compression as a process. Looks a lot like confusion, but isn't ;)
[groan]
Anything you ZIP/ARJ/RAR/BZIP/GZIP up is inherentely lossless. These formats are designed to store an exact copy of information (like documents, executable files, etc.) where you cannot afford to lose a single byte.
Any of these general purpose 'archivers' use lossless compression.
Certain types of files use lossy compression (like JPG, MP3, OGG) -- those will sacrifice part of the information available in order to save diskspace, but those compressions methods are part of the actual file format itself, not a container holding the media.
Any of these general purpose 'archivers' use lossless compression.
Certain types of files use lossy compression (like JPG, MP3, OGG) -- those will sacrifice part of the information available in order to save diskspace, but those compressions methods are part of the actual file format itself, not a container holding the media.
Since you get nearly as much compression by zipping up a bmp or a tiff as you do with making a jpeg, I wonder why jpegs are used so much? Seems silly.
While you can compress 8 bit BMP's fairly well, 24 bit true color images are almost the same size zipped as unzipped, so you gain very little except a bunch of additional overhead.
The JPG algorithm discards information that is designed to have little visual impact. The more quality loss you're willing to allow, the smaller your file will be. Since JPG *does* give you true color images at a significantly compressed size, it's the clear winner there.
If You cannot afford quality loss, you can always use PNG which has better compression than BMP and is lossless as well.
The JPG algorithm discards information that is designed to have little visual impact. The more quality loss you're willing to allow, the smaller your file will be. Since JPG *does* give you true color images at a significantly compressed size, it's the clear winner there.
If You cannot afford quality loss, you can always use PNG which has better compression than BMP and is lossless as well.
you can always use PNG which has better compression than BMP and is lossless as well
And for me, PNG's compress well in ZIP too.
Well, I compressed a 6MB full colour photo tiff into a zip and I'm sure (I think anyway) I got nearly a 10:1 compression rate. But now you've made me question my memory...
TIFF supports LZW compression, which is lossless compression that I'm sure will do about as good a job as ZIP. Saves you having to zip the images at all, and most software can load LZW compressed TIFFs directly.
Ragnar
Ragnar
MrTricks: Depending on the internal compression in the TIFF you may be able to compress them pretty well with ZIP -- but the point remains that the ZIP compressed TIFF won't be (much) smaller than an identical PNG image, or similar.
The advantage of tiffs is that Avid sees a folder of tiffs natively as a sequence - not sure it does with png. (Also not sure it supports LZW but certainly worth a try.)