3.1 get_pnm_type

Read the header contents of a PBM/PGM/PPM/PFM file up to the point of extracting its type. Valid types for a PNM image are as follows:

• PBM_ASCII = 1
• PGM_ASCII = 2
• PPM_ASCII = 3
• PBM_BINARY = 4
• PGM_BINARY = 5
• PPM_BINARY = 6
• PAM = 7 (unimplemented)
• PFM_RGB = 16
• PFM_GREYSCALE = 17

The result (pnm_type) is returned.

3.2 read_pbm_header

Read the header contents of a PBM (portable bit map) file. A PBM image file follows the format:

P1
<X> <Y>
<I1> <I2> ... <IMAX>

A binary PBM image file uses P4 instead of P1 and the data values are represented in binary. Comment lines start with #. < > denote integer values (in decimal). For the PBM format, they can take only the 0 and 1 values. img_xdim and img_ydim correspond to X and Y, respectively. If is_ascii is 1, an ASCII PBM file is assumed; otherwise a binary PBM file is.

3.3 read_pgm_header

Read the header contents of a PGM (portable grey map) file. A PGM image file follows the format:

P2
<X> <Y>
<levels>
<I1> <I2> ... <IMAX>

A binary PGM image file uses P5 instead of P2 and the data values are represented in binary. Comment lines start with #. < > denote integer values (in decimal). img_xdim, img_ydim, and img_colors correspond to X, Y and levels, respectively. If is_ascii is 1, an ASCII PGM file is assumed; otherwise a binary PGM file is.

3.4 read_ppm_header

Read the header contents of a PPM (portable pix map) file. A PPM image file follows the format:

P3
<X> <Y>
<levels>
<R1> <G1> <B1> ... <RMAX> <GMAX> <BMAX>

A binary PPM image file uses P6 instead of P3 and the data values are represented in binary. Comment lines start with #. < > denote integer values (in decimal). img_xdim, img_ydim, and img_colors correspond to X, Y and levels, respectively. Each color component, R, G, and B can take any value from 0 to levels. If is_ascii is 1, an ASCII PPM file is assumed; otherwise a binary PPM file is.

3.5 read_pfm_header

Read the header contents of a PFM (portable float map) file. A PFM image file follows the format:

[PF|Pf]
<X> <Y>
(endianess)
{R1}{G1}{B1} ... {RMAX}{GMAX}{BMAX}

A PFM image file has its data values represented in binary. Comment lines start with #. < > denote integer values (in decimal). ( ) denote floating-point values (in decimal). { } denote floating-point values (coded in binary). img_xdim and img_ydim correspond to X and Y, respectively. If img_type is equal to 1, the PFM image encodes RGB (color) information, otherwise if it is equal to 0, it stores greyscale information. If endianess is negative (-1), the binary data are encoded in little-endian ordering, otherwise if endianess is positive (+1), the data follow big-endian ordering.

3.6 read_pbm_data

Read the data contents of a PBM (portable bit map) file. img_in denotes an array of integer values representing image data. If is_ascii is 1, an ASCII PBM file is assumed; otherwise a binary PBM file is.

3.7 read_pgm_data

Read the data contents of a PGM (portable grey map) file. img_in denotes an array of integer values representing image data. If is_ascii is 1, an ASCII PGM file is assumed; otherwise a binary PGM file is.

3.8 read_ppm_data

Read the data contents of a PPM (portable pix map) file. img_in denotes an array of integer values representing image data. If is_ascii is 1, an ASCII PPM file is assumed; otherwise a binary PPM file is.

3.9 read_pfm_data

Read the data contents of a PFM (portable float map) file. img_in denotes an array of floating-point (float) values representing image data. If img_type is 1, color/RGB image data are assumed; otherwise (0) the image data are in greyscale. A negative endianess indicates little-endian ordering and positive one, big-endian.

3.10 write_pbm_file

Write the contents of a PBM (portable bit map) file. Data stored in array img_out are written to file f. This file is assumed to be already opened under the name img_out_fname. The image data represent an image of size x_size by y_size. x-axis and y-axis scaling factors can be defined by x_scale_val and y_scale_val. linevals determines the emission of newline characters for easier reading of the PBM file data. If is_ascii is 1, an ASCII PBM file is assumed; otherwise a binary PBM file is.

3.11 write_pgm_file

Write the contents of a PGM (portable grey map) file. Data stored in array img_out are written to file f. This file is assumed to be already opened under the name img_out_fname. The image data represent an image of size x_size by y_size. x-axis and y-axis scaling factors can be defined by x_scale_val and y_scale_val. img_colors determines the levels (0 to levels) for the common color component. linevals determines the emission of newline characters for easier reading of the PGM file data. If is_ascii is 1, an ASCII PGM file is assumed; otherwise a binary PGM file is.

3.12 write_ppm_file

Write the contents of a PPM (portable pix map) file. Data stored in array img_out are written to file f. This file is assumed to be already opened under the name img_out_fname. The image data represent an image of size x_size by y_size. x-axis and y-axis scaling factors can be defined by x_scale_val and y_scale_val. img_colors determines the levels (0 to levels) for the common color component. Each R-G-B triplet is printed to a separate line. If is_ascii is 1, an ASCII PPM file is assumed; otherwise a binary PPM file is.

3.13 write_pfm_file

Write the contents of a PFM (portable float map) file. Data stored in array img_out are written to file f. This file is assumed to be already opened under the name img_out_fname. The image data represent an image of size x_size by y_size. x-axis and y-axis scaling factors can be defined by x_scale_val and y_scale_val. If img_type is equal to 1, the PFM image encodes RGB (color) information, otherwise if it is equal to 0, it stores greyscale information. If endianess is negative (-1), the binary data are encoded in little-endian ordering, otherwise if endianess is positive (+1), the data follow big-endian ordering.