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| Home › Support › Breeze Help > "File formats: GIF" options dialog box
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This dialog allows you to specify parameters of GIF file / stream format.
The following options allow you to specify GIF file / stream:
"Color space" group box
This group box allows you to specify a color space used as an internal format
in the GIF image.
Click a radio button in this group box to select a required color space.
"Bit depth" group box
This group box allows you to specify a bit depth of each color component.
Table below shows how many colors there are in the images with the different
bit detpth:
| Bit depth |
Colors in the grayscale image |
Colors in the color palette image |
| 1 |
2 |
2 |
| 2 |
4 |
4 |
| 4 |
16 |
16 |
| 8 |
256 |
256 |
Click a radio button in this group box to select a required bit depth.
"Palette" group box
This group box allows you to specify parameters of algorithms used to build a
palette when "Color palette" radio button in the "Color space" group box is
checked.
if "Standard halftone" radio button is checked then palletized images are made
with the standard for Windows operating system halftone palette. This method is
fast but colors of that palette are not optimal for concrete images.
If "Optimal adaptive octree" radio button is checked then palletized images are
made with the adaptive octree palette (Gervautz-Purgathofer octree algorithm).
This method is slower but colors of that palette are adaptively selected for
every concrete image. As a result quality of a final image is usually much
higher.
"Significant color bits" edit and spin boxes allow setting a number of color
bits used in the octree algorithm. Usually from 4 to 6 bits are enough to make
a good quality palette. Increasing number of bits to 7 and 8 does not usually
improve noticeably quality of palette. Best palette is made when the maximum
number of significant bits, 8, But using a bigger number of bits makes
calculations slower.
"Interlaced" check box
This check box allows you to specify whether internally PNG image will be save
as progressive or interlaced.
Remarks
GIF file format uses a lossless compression algorithm. It means that color
information is not lost in the GIF image during compression itself, and a
quality of an image converted into the GIF format may be the same as it was the
original uncompressed image.
There are two major exceptions from this rule. GIF image internally may be
presented in the different color spaces and with the different color bit depth.
As a result some color information may be lost if during GIF compression:
- Color space of the original image is converted
into another color space with a smaller number of color components.
- Bit depth of the original image is reduced.
GIF color images contain no more than 256 colors. Therefore color information
is lost when 24 bit RGB image is saved as a GIF. Also color information is lost
when original color image is saved as a gray GIF image; or when original image
with 8 bit color depth is saved as a 4 bit GIF image.
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