PGMA Files
Portable Gray Map (ASCII)

PGMA is the ASCII portable gray map format. It is a simple grayscale image description. The definition is as follows:

the typical file extension is ".pgm", but an extension of ".pnm" is also occasionally used.
A "magic number" for identifying the file type. An ASCII PGM file's magic number is the two characters "P2".
Whitespace (blanks, TABs, CRs, LFs).
A width, formatted as ASCII characters in decimal.
Whitespace.
A height, again in ASCII decimal.
Whitespace.
The maximum gray value, again in ASCII decimal.
Whitespace.
Width * height gray values, each in ASCII decimal, between 0 and the specified maximum value, separated by whitespace, starting at the top-left corner of the graymap, proceeding in normal English reading order. A value of 0 means black, and the maximum value means white.

Characters from a "#" to the next end-of-line are ignored (comments). No line should be longer than 70 characters.

Example PGMA file:

        P2
        # feep.pgma
        24 7
        15
        0 0  0  0  0  0  0  0  0 0  0  0  0  0  0  0  0 0  0  0  0  0  0  0
        0 3  3  3  3  0  0  7  7 7  7  0  0 11 11 11 11 0  0 15 15 15 15  0
        0 3  0  0  0  0  0  7  0 0  0  0  0 11  0  0  0 0  0 15  0  0 15  0
        0 3  3  3  0  0  0  7  7 7  0  0  0 11 11 11  0 0  0 15 15 15 15  0
        0 3  0  0  0  0  0  7  0 0  0  0  0 11  0  0  0 0  0 15  0  0  0  0
        0 3  0  0  0  0  0  7  7 7  7  0  0 11 11 11 11 0  0 15  0  0  0  0
        0 0  0  0  0  0  0  0  0 0  0  0  0  0  0  0  0 0  0  0  0  0  0  0

PGMA File Characteristics:

ASCII
Gray
2D
No compression
1 image

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Data and Programs:

PBMA is a data directory which describes ASCII Portable Bit Map files.

PGMB is a data directory which describes binary Portable Gray Map files.

PPMA is a data directory which describes ASCII Portable Pixel Map files.

Reference:

the NETPBM homepage.

Programs to create a PGMA file:

The gnuplot command "set terminal pbm gray" will cause the graphics information to be written to a PGM file.

Programs and routines to read a PGMA file:

MATLAB can read a PGMA file with a command like A=imread('file','PGM').
pgma_io a set of C++ routines;
pgma_io a set of FORTRAN90 routines;
pgma_io, a set of MATLAB functions.
The Visual Toolkit routine vtkPNMReader can read an ASCII PGM file into VTK.

Programs and routines to write a PGMA file:

MATLAB can write a PGMA file with a command like imwrite(a,'filename','PGM').
pgma_io a set of C++ routines;
pgma_io a set of FORTRAN90 routines;
pgma_io, a set of MATLAB functions.
The Visual Toolkit routine vtkPNMWriter can write a VTK image to an ASCII PGM file.

Programs to view a PGMA file include:

AVS includes a module read_any_image which can view a PGMA file;
GIMP, the GNU Image Manipulation Program, can view a PGMA file.
gqview, a Linux image viewing program, can view a PGMA file.
imgview, an image viewing program from ImageVision can view a PGMA file.

MATLAB can display a PGMA file, once it is read in, with a command like


            A = imread ( 'file.pgm', 'PGM' )
            image ( A )

xv can view a PGMA file on a unix system by a command like
```
            xv file.pgm
          
```

Programs to convert a PGMA file to another format:

cjpeg can convert a PGM file to JPEG format.
convert, a program that is part of ImageMagick, can convert a PGMA file to BMP, CGM, EPS, FIG, FITS, GIF, JPG, PBM, PDF, PGM, PNG, PNM, PPM, PS, RGB, TIF, XBM or XPM format.
GIMP, the GNU Image Manipulation Program, can read a PGMA file and write out a copy in a variety of formats.
PGMA_TO_PGMB is a C++ program which can convert a PGMA file to PGMB format.
The NETPBM program PGMTOFITS converts a PGMA file to FITS format.
xv can read a PGMA file and write out a copy in BMP, FIT, GIF, JPG, PBM, PPM, RGB or TIF format.

Programs to convert a file to PGMA format:

convert, a program supplied with ImageMagick, can convert a BMP, CGM, EPS, FIG, FITS, GIF, JPG, PBM, PDF, PGM, PNG, PNM, PPM, PS, RGB, TIF, XBM or XPM file to PGMA format. However, to force the ASCII format, you must include the switch "-compress none".
djpeg converts a JPEG file to PGMA format.
GIMP, the GNU Image Manipulation Program, can read a file in a variety of formats, and write it out as a PGMA file.
The NETPBM program FITSTOPGM converts a FITS file to PGMA format.
PGMB_TO_PGMA is a C++ program which can convert a PGMB file to PGMA format.
xv can read a file in a BMP, FIT, GIF, JPG, PBM, PPM, RGB or TIF format, and write it out as a PGMA file.

Sample PGMA files:

baboon.ascii.pgm, a 512 by 512 image of a baboon.
baboon.png, a PNG image.
balloons.ascii.pgm, a 640x480 image of a couple, with balloons.
balloons.png, a PNG image.
barbara.ascii.pgm, a 512x512 image
barbara.png, a PNG image.
body1.ascii.pgm
body1.png, a PNG image.
body2.ascii.pgm
body2.png, a PNG image.
body3.ascii.pgm
body3.png, a PNG image.
brain_398.ascii.pgm
brain_398.png, a PNG image.
brain_492.ascii.pgm
brain_492.png, a PNG image.
brain_508.ascii.pgm
brain_508.png, a PNG image.
brain_604.ascii.pgm
brain_604.png, a PNG image.
columns.ascii.pgm, a 640x480 image of a person standing by some columns;
columns.png, a PNG image.
f14.ascii.pgm
f14.png, a PNG image.
feep.ascii.pgm, a simple 7 by 24 example that displays "FEEP" in block letters.
feep.png, a PNG image.
foliage.ascii.pgm
foliage.png, a PNG image.

, a PNG image.

, a PNG image.

hands.ascii.pgm
hands.png, a PNG image.
handsmat.ascii.pgm
handsmat.png, a PNG image.
lena.ascii.pgm a 512x512 image.
lena.png, a PNG image.
marcie.ascii.pgm
marcie.png, a PNG image.
mountain.ascii.pgm
mountain.png, a PNG image.
pbmlib.ascii.pgm, a 600x200 image created by PBMLIB.
pbmlib.png, a PNG image.
saturn.ascii.pgm
saturn.png, a PNG image.
screws.ascii.pgm
screws.png, a PNG image.
surf.ascii.pgm
surf.png, a PNG image.
totem.ascii.pgm
totem.png, a PNG image.
tracks.ascii.pgm, a 300x200 image that looks like tracks.
tracks.png, a PNG image.
venus1.ascii.pgm
venus1.png, a PNG image.
venus2.ascii.pgm
venus2.png, a PNG image.
x31_f18.ascii.pgm
x31_f18.png, a PNG image.

You can go up one level to the DATA page.

Last revised on 22 September 2009.

PGMA Files Portable Gray Map (ASCII)