starlifter
Deity
- Joined
- Jun 17, 2001
- Messages
- 4,210
What is advantages & disadvanatages to using the following formats for an avatar: JPEG, GIF, BMP, TIFF PSD
JPEG - Lossy, true color (16.7 million), best in natural life (not straight edges & same-colored areas). Variable compression (small size/poorer quality to larger size/higher quality). Can be interlaced (aka "progressive").
GIF - Lossless (in detail), but can be lossy in color shifts because of its small palette (256 colors), best for most graphics, cartoons, things with continious stretches of the same exact color (they will compress more). Can have transparant background, and can be interlaced (aka "progressive"). The GIF89a standard allows animations, text blocks, and extensions.
BMP - Not compressed; Normally 256 color palette, but some software has options for 16 bit and 24 bit in addition to 8 bit color. Best for graphics at 256 color. At True Color (24 bit, 16.7 million), BMP will store a lossless image with exact color... but the file is huge, and generally not suitable for websites and internet transfer due to large size.
TIFF - Several companies developed the Tagged Image Format (including Aldus and Silicon Graphics) to be the ultimate image file format. It is lossless, and true color, and has many ways of compression. It can actually support up to 48 bit color (true color is only 24 bit). A TIFF good for archiving an exact copy of the work, but while it is smaller than the BMP, it is generally larger than GIF and JPEG (unless using one of the newest experimental TIFF compression formats). I typically save edits in TIFF, and then convert them to GIF or JPEG when the result is done. Future re-editing is done from the TIFF, not JPEG and generally not the GIF.
PSD - Photoshop Document. This is the ultimate format if you use high end editing software, since it can store channels, layers, and lots more information than other formats. It is lossless and exact color, naturally. And it is big. Many programs cannot read it, and PSD is not good for Web/Internet usage... but excellent (better than TIFF) for high end editing and use.
Also, which are lossless and which are lossy?
The bit battern of the image is lossless in .BMP and .GIF, but the colors may be altered (approximated), depending on color depth selected, # of original colors, palette transform, method, the pallet itself (e.g., windows standard, netscape standard, optmization method, etc.).
Which is generally best for graphics & cartoons?
GIFs. Typical graphics are usually limited in colors (GIFs are limited to max of 256), and the actual bit pattern is lossless. The color may be shifted (see prior answer).
Which is generally best for natural life?
JPEG, since it uses 24bit color, and a cosine transform to approximate what looks "best" to the human eye.
Which can have transparent background?
GIFs.
To clarify some of Piny's answers, JPEGs are always 24-bit color. Layers are not what gives transparancy and animation. Animation is simply consecutive images stored in one file, according to the GIF89a specification. Transparancy is setting a particular color (the "background color") to "transparant", which means the image's pixels of that color are not rendered when displayed, and whatever is underneath shows through. There is much development in the world of graphic standards, but the problem in the end for any "latest, greatest" thing is widespread compatibility. GIF and JPEG are no longer the absolute best for web use, but they are the most universal and compatible!
Well, King of Camelot... your question!
JPEG - Lossy, true color (16.7 million), best in natural life (not straight edges & same-colored areas). Variable compression (small size/poorer quality to larger size/higher quality). Can be interlaced (aka "progressive").
GIF - Lossless (in detail), but can be lossy in color shifts because of its small palette (256 colors), best for most graphics, cartoons, things with continious stretches of the same exact color (they will compress more). Can have transparant background, and can be interlaced (aka "progressive"). The GIF89a standard allows animations, text blocks, and extensions.
BMP - Not compressed; Normally 256 color palette, but some software has options for 16 bit and 24 bit in addition to 8 bit color. Best for graphics at 256 color. At True Color (24 bit, 16.7 million), BMP will store a lossless image with exact color... but the file is huge, and generally not suitable for websites and internet transfer due to large size.
TIFF - Several companies developed the Tagged Image Format (including Aldus and Silicon Graphics) to be the ultimate image file format. It is lossless, and true color, and has many ways of compression. It can actually support up to 48 bit color (true color is only 24 bit). A TIFF good for archiving an exact copy of the work, but while it is smaller than the BMP, it is generally larger than GIF and JPEG (unless using one of the newest experimental TIFF compression formats). I typically save edits in TIFF, and then convert them to GIF or JPEG when the result is done. Future re-editing is done from the TIFF, not JPEG and generally not the GIF.
PSD - Photoshop Document. This is the ultimate format if you use high end editing software, since it can store channels, layers, and lots more information than other formats. It is lossless and exact color, naturally. And it is big. Many programs cannot read it, and PSD is not good for Web/Internet usage... but excellent (better than TIFF) for high end editing and use.
Also, which are lossless and which are lossy?
The bit battern of the image is lossless in .BMP and .GIF, but the colors may be altered (approximated), depending on color depth selected, # of original colors, palette transform, method, the pallet itself (e.g., windows standard, netscape standard, optmization method, etc.).
Which is generally best for graphics & cartoons?
GIFs. Typical graphics are usually limited in colors (GIFs are limited to max of 256), and the actual bit pattern is lossless. The color may be shifted (see prior answer).
Which is generally best for natural life?
JPEG, since it uses 24bit color, and a cosine transform to approximate what looks "best" to the human eye.
Which can have transparent background?
GIFs.
To clarify some of Piny's answers, JPEGs are always 24-bit color. Layers are not what gives transparancy and animation. Animation is simply consecutive images stored in one file, according to the GIF89a specification. Transparancy is setting a particular color (the "background color") to "transparant", which means the image's pixels of that color are not rendered when displayed, and whatever is underneath shows through. There is much development in the world of graphic standards, but the problem in the end for any "latest, greatest" thing is widespread compatibility. GIF and JPEG are no longer the absolute best for web use, but they are the most universal and compatible!
Well, King of Camelot... your question!
