spottopgm, rlatopam, rgb3toppm, ppmtorgb3: add pages (#15354)

* fix ci

* spottopgm, rlatopam, rgb3toppm, ppmtorgb3: add pages

* fix typo

pages/common/ppmtorgb3.md

@@ -0,0 +1,9 @@
+# ppmtorgb3
+
+> Separate the color components of a PPM file into three separate PGM files.
+> See also: `rgb3toppm`.
+> More information: <https://netpbm.sourceforge.net/doc/ppmtorgb3.html>.
+
+- Separate the color components of a PPM file, saving the outputs to `file.red`, `file.grn` and `file.blu`:
+
+`ppmtorgb3 {{path/to/file.ppm}}`

pages/common/rgb3toppm.md

@@ -0,0 +1,9 @@
+# rgb3toppm
+
+> Combine three PGM images into one PPM image.
+> See also: `ppmtorgb3`.
+> More information: <https://netpbm.sourceforge.net/doc/rgb3toppm.html>.
+
+- Combine three PGM images (representing red, green and blue color components) into one PPM image:
+
+`rgb3toppm {{path/to/red_file.ppm}} {{path/to/green_file.ppm}} {{path/to/blue_file.ppm}} > {{path/to/output.ppm}}`

pages/common/rlatopam.md

@@ -0,0 +1,8 @@
+# rlatopam
+
+> Convert Alias/Wavefront RLA and RPF image files to Netpbm format.
+> More information: <https://netpbm.sourceforge.net/doc/rlatopam.html>.
+
+- Convert the specified SPOT image to PGM format:
+
+`rlatopam {{path/to/file}} > {{path/to/output.pam}}`

pages/common/spottopgm.md

@@ -0,0 +1,16 @@
+# spottopgm
+
+> Convert a SPOT satellite image to PGM format.
+> More information: <https://netpbm.sourceforge.net/doc/spottopgm.html>.
+
+- Convert the specified SPOT image to PGM format:
+
+`spottopgm {{path/to/file.spot}} > {{path/to/output.pgm}}`
+
+- Extract the specified color channel:
+
+`spottopgm -{{1|2|3}} {{path/to/file.spot}} > {{path/to/output.pgm}}`
+
+- Extract the specified rectangle from the input image:
+
+`spottopgm {{first_col first_row last_col last_row}} {{path/to/file.spot}} > {{path/to/output.pgm}}`