Compress Photo
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How to compress photo files and obtain smaller files for your photos and images.
In a broad sense, to compress photo files means to save digital photos in files that are smaller than regular bmp files.
We will consider 2 cases, the lossless image formats and the lossy image formats.
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Lossless image formats
Lossless formats are formats containing all the information from the original photo.
When you save photos in lossless compressed format files,
different methods are applied in order to get a smaller file,
but this file contains all the original information in a more compact form. Nothing is lost.
Apart from bmp
-a compressed variant of bmp is called rle-
the lossless format that most photo software is able to handle is png.
Another often used format, that can be uncompressed or compressed using various algorithms, is tiff.
Gif is a lossless format too, but being limited to 256 colors, it is seldom a good choice for photos.
The disadvantage of these formats is that after applying a compression algorithm you must take what you get,
you can not make your file smaller to your liking.
The advantage is that these formats are perfect to keep unaltered originals of your photos.
Lossy image formats
Lossy image formats
-as the name suggests- will lose some information from the original.
When you compress photo files saved under these formats,
you will choose how much quality you accept to lose and following how small you want the file to be.
The most known of these formats is jpeg of course.
The advantage of compressed jpeg photos and images is that you can make pretty small files for the web
that load rapidly when people visit your pages. That a little bit quality has gone lost is mostly not a problem.
More information about crunching jpeg images or shrinking jpegs, how to do it, how to do it better and different examples,
at the page about how to
compress photo files in the jpeg format.
Examples:
image size = 220 x 165 pixels
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| file format |
file size |
| bmp file, lossless |
107 kbytes |
| tiff file, lzw compression, lossless |
101 kbytes |
| png file, lossless |
80 kbytes |
| jpeg file, lossy |
11 kbytes |
Please read also the detailed page about how to
compress photo files in the jpeg format
with various examples.
