2D grayscale/color files: .png, .jpeg, .gif, .pnm, .tif, .bmp, ...

3D volumetric files: .dcm, .hdr, .nii, .cube, .pan, .inr, .pnk, ...

Video files: .mpeg, .avi, .mp4, .mov, .ogg, .flv, ...

Generic text or binary data files: .gmz, .cimg, .cimgz, flo, ggr, gpl, .dlm, .asc, .pfm, .raw, .txt, .h.

3D mesh files: .off, .obj.

Video files: Only sub-frames of an image sequence may be loaded, using the input expression filename.ext,[first_frame[,last_frame[,step]]]. Set last_frame==-1 to tell it must be the last frame of the video. Set step to 0 to force an opened video file to be opened/closed. Output framerate and codec can be also set by using the output expression filename.avi,_fps,_codec,_keep_open where keep_open can be { 0 | 1 }. codec is a 4-char string (see http://www.fourcc.org/codecs.php ) or 0 for the default codec. keep_open tells if the output video file must be kept open for appending new frames afterwards.

.cimg[z] files: Only crops and sub-images of .cimg files can be loaded, using the input expressions filename.cimg,N0,N1, filename.cimg,N0,N1,x0,x1, filename.cimg,N0,N1,x0,y0,x1,y1, filename.cimg,N0,N1,x0,y0,z0,x1,y1,z1 or filename.cimg,N0,N1,x0,y0,z0,c0,x1,y1,z1,c1. Specifying -1 for one coordinates stands for the maximum possible value. Output expression filename.cimg[z][,datatype] can be used to force the output pixel type. datatype can be { auto | bool | uint8 | int8 | uint16 | int16 | uint32 | int32 | uint64 | int64 | float32 | float64 }.

.raw binary files: Image dimensions and input pixel type may be specified when loading .raw files with input expression filename.raw[,datatype][,width][,height[,depth[,dim[,offset]]]]]. If no dimensions are specified, the resulting image is a one-column vector with maximum possible height. Pixel type can also be specified with the output expression filename.raw[,datatype]. datatype can be the same as for .cimg[z] files.

.yuv files: Image dimensions must be specified when loading, and only sub-frames of an image sequence may be loaded, using the input expression filename.yuv,width,height[,chroma_subsampling[,first_frame[,last_frame[,step]]]. chroma_subsampling can be { 420 | 422 | 444 }. When saving, chroma subsampling mode can be specified with output expression filename.yuv[,chroma_subsampling].

.tiff files: Only sub-images of multi-pages tiff files can be loaded, using the input expression filename.tif,_first_frame,_last_frame,_step. Output expression filename.tiff,_datatype,_compression,_force_multipage,_use_bigtiff can be used to specify the output pixel type, as well as the compression method. datatype can be the same as for .cimg[z] files. compression can be  { none (default) | lzw | jpeg }. force_multipage can be { 0:no (default) | 1:yes }. use_bigtiff can be { 0:no | 1:yes (default) }.

.pdf files: When loading a file, the rendering resolution can be specified using the input expression filename.pdf,resolution, where resolution is an unsigned integer value.

.gif files: Animated gif files can be saved, using the input expression filename.gif,fps>0,nb_loops. Specify nb_loops=0 to get an infinite number of animation loops (this is the default behavior).

.jpeg and .webp files: The output quality may be specified (in %), using the output expression filename.jpg,30 (here, to get a 30% quality output). 100 is the default.

.png files: The bit depth can be specified (8 or 16), using the output expression filename.png,16 (here, to get a 16 bit depth output file). By default, G'MIC guesses the best bit depth automatically.

.mnc files: The output header can set from another file, using the output expression filename.mnc,header_template.mnc.

.pan, .cpp, .hpp, .c and .h files: The output datatype can be selected with output expression filename[,datatype]. datatype can be the same as for .cimg[z] files.

.gmic files: These filenames are assumed to be G'MIC custom commands files. Loading such a file will add the commands it defines to the interpreter. Debug information can be enabled/disabled by the input expression filename.gmic[,add_debug_info] where debug_info can be { 0:false | 1:true }.

Inserting ext: on the beginning of a filename (e.g. jpg:filename) forces G'MIC to read/write the file as it would have been done if it had the specified extension .ext.