WebmasterCricket
<font color=blue>Administrator<br><font color=red>
- Joined
- Jan 29, 2001
In the past (and probably right now) there has been confusion on just what the different image formats mean. This thread will hopefully straighten out what and why with a little extra info thrown in for good measure. This should either make you say Oh, now I understand! or Ok, now Im really confused! Either way, I hope this is helpful to someone.
What the heck is a gif?
Gif stands for Graphics Interchange Format. It is a proprietary, non-lossy (does not loose bits during compression) encoding/decoding scheme invented by CompuServe in 1987 called LZW (Lempel Zev Welch). This format is currently patented by Unisys who has been arguing about compensation for a while now from companies applications that save images in this format by default (irrelevant to me and you at this time, just thought you might like to know).
This has to be the most widely used format on the Internet (right now). The reason for its popularity comes from a combination of factors:
1) Compression is outstanding
2) Allows interlacing (this feature lets an image first display a low quality version and then add detail to the image until all of the information has been displayed (it kind of fades in))
3) Transparency is now supported in the 89a version which allows you to designate 1 color as being transparent meaning you can see whatever happens to be behind the image, through it
4) Frame progression (animation) allows you to combine multiple frames that swap out each other giving you an illusion of animation or images changing in banners
5) Labels can be attached to the image for copyright and remark purposes (needs to be edited to see this)
One of gifs weakest points is also one of its strongest and that is the magic number 256. Gifs can display up to 256 colors or less. 256 limits you from most photos that contain millions of colors but on the other side of the coin, it can support lower numbers of colors and thus takes up less bandwidth to transmit.
Due to the limitations, gifs should be used where colors are distinct and low in number.
What the heck is a jpg?
Jpg (actually jpeg) stands for Joint Photographic Experts Group. It was designed for artists and photographers to allow transmission of high color, decent quality photographs across the Internet and for digital editing. It should be used when color is imperative, and ONLY then.
There are basically 2 things that you need to know about jpegs:
1) Supports millions of colors
2) Uses a lossy type compression (it will dump bits of the image to save space thus reducing the quality level as well). The compression amount can be controlled to get a happy medium between size and quality.
The loss of quality is generally made up in color depth. Since you can get better optical resolution using colors rather than just data, this made people happy.
Due to the file size and color amount, jpegs should be used where gradients and high color counts are needed and NO WHERE ELSE. You are just wasting space time and bandwidth otherwise.
What the heck is a bmp?
Bmp stands for bit mapped not bitmap. I know that seems trivial, but they are two different things. Bitmap is a specific type of image meaning that there is a series of bits that are placed in locations from a map or matrix. All three types of images that I have explained so far are bitmaps but only one is bit mapped and that is bmp.
Bmps are a 1 to 1 correlation of color and location in a matrix. There is no compression and thus no loss of bits. There is NO PLACE for these on the internet other than download purposes for extremely high detail images for use in printing and possibly cool Disney wallpaper
. There is always a better format for web usage.
There are tons of other less common types of image formats in use today that are somewhat better and worse than the above 3. These include combinations of both bitmap and vector images , transparency support, animation support and decent compression algorithms.
Eventually, better counterparts will replace most image formats, but for now, these should do just fine.
Just in case you are wondering, when I move images from one program to another, I dont use ANY of these formats. I use png (Portable Network Graphics) format or vector images whenever possible. If you use them yourself, you know why. If you dont, then dont sweat it.
Any questions?
What the heck is a gif?
Gif stands for Graphics Interchange Format. It is a proprietary, non-lossy (does not loose bits during compression) encoding/decoding scheme invented by CompuServe in 1987 called LZW (Lempel Zev Welch). This format is currently patented by Unisys who has been arguing about compensation for a while now from companies applications that save images in this format by default (irrelevant to me and you at this time, just thought you might like to know).
This has to be the most widely used format on the Internet (right now). The reason for its popularity comes from a combination of factors:
1) Compression is outstanding
2) Allows interlacing (this feature lets an image first display a low quality version and then add detail to the image until all of the information has been displayed (it kind of fades in))
3) Transparency is now supported in the 89a version which allows you to designate 1 color as being transparent meaning you can see whatever happens to be behind the image, through it
4) Frame progression (animation) allows you to combine multiple frames that swap out each other giving you an illusion of animation or images changing in banners
5) Labels can be attached to the image for copyright and remark purposes (needs to be edited to see this)
One of gifs weakest points is also one of its strongest and that is the magic number 256. Gifs can display up to 256 colors or less. 256 limits you from most photos that contain millions of colors but on the other side of the coin, it can support lower numbers of colors and thus takes up less bandwidth to transmit.
Due to the limitations, gifs should be used where colors are distinct and low in number.
What the heck is a jpg?
Jpg (actually jpeg) stands for Joint Photographic Experts Group. It was designed for artists and photographers to allow transmission of high color, decent quality photographs across the Internet and for digital editing. It should be used when color is imperative, and ONLY then.
There are basically 2 things that you need to know about jpegs:
1) Supports millions of colors
2) Uses a lossy type compression (it will dump bits of the image to save space thus reducing the quality level as well). The compression amount can be controlled to get a happy medium between size and quality.
The loss of quality is generally made up in color depth. Since you can get better optical resolution using colors rather than just data, this made people happy.
Due to the file size and color amount, jpegs should be used where gradients and high color counts are needed and NO WHERE ELSE. You are just wasting space time and bandwidth otherwise.
What the heck is a bmp?
Bmp stands for bit mapped not bitmap. I know that seems trivial, but they are two different things. Bitmap is a specific type of image meaning that there is a series of bits that are placed in locations from a map or matrix. All three types of images that I have explained so far are bitmaps but only one is bit mapped and that is bmp.
Bmps are a 1 to 1 correlation of color and location in a matrix. There is no compression and thus no loss of bits. There is NO PLACE for these on the internet other than download purposes for extremely high detail images for use in printing and possibly cool Disney wallpaper
. There is always a better format for web usage.There are tons of other less common types of image formats in use today that are somewhat better and worse than the above 3. These include combinations of both bitmap and vector images , transparency support, animation support and decent compression algorithms.
Eventually, better counterparts will replace most image formats, but for now, these should do just fine.
Just in case you are wondering, when I move images from one program to another, I dont use ANY of these formats. I use png (Portable Network Graphics) format or vector images whenever possible. If you use them yourself, you know why. If you dont, then dont sweat it.
Any questions?
