Graphics Interchange Format (GIF)
GIF file format is used to hold and transfer images in index color mode (not more than 256). Settings of this format are adjusted with the help of the following parameters:
- colors - number of colors (default - 255)
- quant - quantization levels (default - 8)
- dither - dithering (default - yes)
- multipage - multipage option (default - "AS IS")
- interlace - save interlaced (default- no)
- opt_lossless - optimize without quality loss (default - no)
Colors parameter specifies the number of colors in the resulting file. Its allowed walues are whole numbers from 2 to 256.
The default value is: 255.
Quant parameter reduces the number of distinct colors used in an image while preserving visual image quality. The allowed values of Quantization parameter are whole numbers from 0 to 8. The default value is: 8.
Dither is a form of noise, or 'erroneous' signal or data which is added to sample data to minimize quantization error. The allowed values of dither parameter are : yes and no.
The default value is: yes.
Multipage parameter specifies the way of saving output images: as single files or one multipage file. Its allowed values are:
- as_is - all converted images are saved to resulting files in accordance with the structure of source files.
- separate_pages - all source files, single-page as well as multipage, will be saved as separate single-page files.
- multipage - all source images will be saved to one multipage file.
- append - all source images will be added to the specified multipage file.
The default value is: as_is.
Interlace parameter activates or deactivates interlacing of output files. Its allowed values are:
- yes - interlacing of output files is activated.
- no - interlacing of output files is deactivated.
The default value is: no.
Opt_lossless parameter activates/deactivates lossless image optimizing. Its allowed values are:
- yes - optimizing of output files is activated.
- no - optimizing of output files is deactivated.
The default value is: no.
ICPCL.exe -convertto gif colors:128 quant:4 dither:no multipage:append interlace:yes opt_lossless:yes -source "C:\Original files" -dest "C:\Converted files"
When creating multipage files, the order of their pages is specified by the order of converted images (that is, the way they are sorted with the help of -sort key).
If interlace parameter is activated, output files are created as follows: rows # 1, 5, 10 etc. are written first, rows # 2, 6, 11 etc. are written next, etc. This results in small increase of the file size. The main advantage of this mode is the way such images are loaded (rows # 1, 5, 10 etc. during the first pass, rows # 2, 6, 11 etc. during the second pass). The loaded rows are stretched to fill whole image space, so that users could understand what this image is like without waiting for it to load completely. This option is mostly used on the Web.