-F filetype
The -F parameter determines the image file type that will be saved. If -F is not specified, the file type will be a Windows BMP file. If the -multipage option is used, the file will be a multipaged image file (only TIFF, PCX, PDF, and PostScript formats allow multi-page image files).
The valid values for -F are as follows:
bmp |
Windows BMP file |
emf |
Enhanced Windows meta-file format |
gif |
Compuserve GIF format |
ico |
Windows ICON format |
icov |
Vista-compatible ICON format (width/height > 255 pixels) |
jpeg |
JPEG format |
jp2 |
JPEG-2000 format |
pcx |
PCX format |
Adobe PDF format |
|
png |
Portable Network Graphics (PNG) format |
psd |
Adobe Photoshop format |
ps1 |
PostScript Level 1 format |
ps2 |
Postscript Level 2 format |
tga |
Targa Format |
tif1 |
uncompressed TIFF image |
tif2 |
TIFF using PackBits compression |
tif3 |
TIFF using Group 3 Fax compression |
tif4 |
TIFF using Group 4 Fax compression |
tif5 |
TIFF using JPEG compression |
tif6 |
TIFF using Flate compression |
tif7 |
TIFF using LZW compression |
wbmp |
Wireless Bitmap format. |
wmf |
Windows Meta File. |
Example: Acquire to a Group 3 TIFF format, the file is called mytif.tif:
DTWAIN_TwainSave("-F tif3 -f mytif.tif");
If the device cannot save to the file type specified, this will usually mean one of the following:
| • | There was a general problem in saving the file (disk full, user does not have write access to the drive and directory, etc.) or |
| • | TWAIN device did not or could not acquire the image in the proper format. For example, a Group 3 TIFF is specified (-F tif3), however the device acquired a color image. Color images cannot be saved to Group 3 or Group 4 TIFF files. You would see the following in a command-line window if the -verbose option is specified, or in the log file specified by -verboselog: |
The error states that the device is attempting to transfer 8 bit images (usually color or gray scale), but the image format specified (TIFF Group 3) does not support color or gray-scale images.
If the device's user interface is shown, the user may have chosen an incorrect type that matches the format given on the DTWAIN_TwainSave command line. Therefore it is highly recommended that if you plan to use DTWAIN_TwainSave, and the device's user interface will be available to the user, to select a file format that gives you the most supported types of colors. For example BMP supports both monochrome, gray-scale, and color images, as do all forms of TIFF except for Group 3, Group 4 TIFF, and TIFF-JPEG.
Here are the list of file types, and the bits-per-pixel supported for each one:
Below is a table describing the valid bit-depths for each file type:
File Type Bit Depth
bmp |
Any bit depth |
ico, icov |
8, 24 |
jpeg, jp2 |
8, 16, or 24 |
pcx |
1, 8 or 24 |
tga |
8 or 24 |
tif1, tif2, tif5, tif7 |
1, 4, 8, 16, or 24 |
tif3, tif4 |
1 |
tif6 |
8, 16, 24 |
emf, wmf |
24 |
gif |
1, 8 |
png |
1, 8, 16, or 24 |
psd |
24 |
1, 8, 16, 24 |
|
ps1, ps2 |
1, 8, 16, 24 |
wbmp |
1 |
1 bit-per-pixel are monochrome (black/white) images.
4 bits-per-pixel are usually gray-scale images.
8 bits-per-pixel are usually gray-scale and 256 color images.
16 and 24 bits-per-pixel are usually color images.
Note: Bit depths higher than 24 should be stored as bmp files.
Default Setting:
The image type is bmp (Windows BMP).