View Full Version : Image Type Uses
j o r d a n 2 0 0 4
29th November 2001, 23:39
what are all the most common image types and what do they excel in?
So far i know:
Bitmap: High Quality - Larger File
Jpeg: Degradding Quality - Smaller File
Gif: Ok Quality - Animation, smaller than bitmap, transparency
Png: Ok quality - transparency
Psd: bad to extremely good quality - transparency, layers, large file only openable by photoshop and quarkXpress other adobe products.
Correct me if im wrong and add any file types i missed.
i wanna have this list so i can be as efficent as possible.
30th November 2001, 06:16
A PSD only has extremely good quality (lossless), and is only used in production. No one should ever publish with this format because it contains a lot of data (notes, masks, channels, orginal layers) that is completely useless to anyone unless they are supposed to edit the image.
Tiffs are good for extremely large pictures (5+ Megs). If you try to open a Jpeg that is 5 or more Megs, you will regret it... but tiffs are painless in that aspect.
30th November 2001, 12:00
PNG is high quality, as high as BMP, but with the added bonus of alpha transparency and better compression.
30th November 2001, 14:00
Just a note of interest, Irfanview http://www.irfanview.com can open PSDs and save them to other formats. It's free and can handle almost all image formats available. Be sure to get the plugin pack for it too!
30th November 2001, 17:42
Just to reiterate, PNG is perfect (lossless) quality. However, many paint programs have very shitty compression algorithms (Photoshop in particular.) So, we like to use the utility pngcrush (http://pmt.sourceforge.net/pngcrush/ It works super good. It compresses every last little byte out of your PNG files (and still losslessly). We use it on the default skin to save about 180kbytes off the size.
We use the options "pngcrush -brute -reduce", which makes it try every possible variation in the compression schemes and write out the smallest one.
Another thing you can do to shrink PNG size is to save it out as grayscale (if that makes sense for your bitmap of course) or to reduce the colors down to 8-bit mode (if that looks ok). Now, those are lossy operations, but pngcrush will be able to compress them even better if you do that.
30th November 2001, 21:40
JPG can be high quality, its just big.
GIF is good for large areas with fewer colors, it can have a max of 256 colors.
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