It seems that every image processing software package has one or more of its own image file formats. Even in packages where external formats have been adopted, changes in those formats literally made them different formats. There are many conversion programs dealing with specific pairwise conversions - not a particularly efficient solution to the user. Bsoft attempts to deal with images as generalized constructs, encapsulating most of the information embedded in the image files in an internal structure. The notion of conversion is now trivial, as reading and writing of multiple file formats are supported. The limiting factor in this is still the limitations within each file format. E.g., you cannot expect file formats designed for single images (such as MRC and EM) to store multiple images (whether 2D or 3D).
Table 5.2. Image file format features (as implemented in Bsoft)
| Image format | Extensions | Data types | Dimensions | Fourier/Complex | Sampling Info | Remarks |
|---|---|---|---|---|---|---|
| ASCII | .asc, .txt | (text) | 3D, single | List | No | |
| BioRad | .pic | b, u | 3D, single | No | No | Confocal microscopy |
| Brix | .brx | b | 3D, single | No | Indirect | O package, Xtal |
| Brookhaven STEM | .dat | b | 2D, double interleaved | No | One value | STEM corrections applied on reading |
| CCP4 | .map, .ccp, .ccp4 | c, s, f, S, F | 3D, single | Centered hermitian | Indirect | Xtal |
| Digital Instruments | .di | s | 2D, double | No | No | No write support |
| Digital Micrograph | .dm, .dm3 | b, s, i, f, F | 2D, single | No | No | Proprietary format |
| Ditabis image plate reader | .IPL, .IPH, .IPR, .IPC | s, i | 2D, single | No | Two values | Micron package |
| DSN6 | .dsn6, .dn6, .omap | b | 3D, single | No | Indirect | O package, Xtal |
| EM | .em | b, s, i, f | 3D, single | Hermitian | No | EM package |
| Goodford | .pot | f | 3D, single | No | One value | Electrostatic potential |
| GRD | .grd | b, f | 3D, single | No | Three values | Basel MIH format |
| HKL | .hkl | (text) | 3D, single | List | No | Structure factor format |
| Imagic | .img (.hed) | b, s, f, F | 2D, multiple | Centered | No | Header in a separate file |
| Image Magick | .miff | b (RGB) | 2D, multiple | No | No | X-window display program |
| JPEG | .jpg, .jpeg | b (RGB) | 2D, single | No | No | Web image format |
| MFF | .mff | b, f | 3D, single | No | Three values | Whatif package |
| MRC | .mrc | b, s, f, S, F | 3D, single | Centered hermitian | Indirect | MRC package |
| PIC BP | .bp | b | 2D, single | No | No | PIC package |
| PIF | .pif | b, s, i, f, S, F | 3D, multiple | Binary list | Three values | PFT/EM3DR package |
| PNG | .png | b, s (RGB) | 2D, single | No | Two values | Network image format |
| Spider | .spi | f | 3D, multiple | Hermitian | One value | Spider package |
| Suprim | .spm, .sup, .f | b, s, i, f (RGB) | 3D, single | Standard | One value | Suprim package |
| TIFF | .tif, .tiff | b, s, i, f (RGB) | 3D, multiple | No | Two values | Only the byte data type is common |
Sampling information: The sampling or voxel/pixel size information is represented as three values (for x, y and z), or two values (TIFF only provides for sampling information in the x and y directions), or one value (for all three directions). Crystallographic formats (such as CCP4 and MRC) give sampling indirectly, calculated from the ratios of the unit cell dimensions and the voxel size of the unit cell (this leads to inaccuracies due to round-off).