PPMA Files
Portable Pixel Map (ASCII)

PPMA is the ASCII version of the portable pixel map PPM format. It is a simple RGB color image description. The definition is as follows:

• the typical file extension is ".ppm", but an extension of ".pnm" is also occasionally used.
• A "magic number" for identifying the file type. An ASCII PPM file's magic number is the two characters "P3".
• Whitespace (blanks, TABs, CRs, LFs).
• A width, formatted as ASCII characters in decimal.
• Whitespace.
• A height, again in ASCII decimal.
• Whitespace.
• The maximum color-component value, again in ASCII decimal.
• Whitespace.
• Width * height pixels, each three ASCII decimal values between 0 and the specified maximum value, starting at the top-left corner of the pixmap, proceeding in normal English reading order. The three values for each pixel represent red, green, and blue, respectively; a value of 0 means that color is off, and the maximum value means that color is maxed out.

Example PPMA File:

        P3
        # feep.ppma
        4 4
        15
         0  0  0  0  0  0    0  0  0   15  0 15
         0  0  0  0 15  7    0  0  0    0  0  0
         0  0  0  0  0  0    0 15  7    0  0  0
        15  0 15  0  0  0    0  0  0    0  0  0
      

PPMA File Characteristics:

• ASCII
• RGB color
• 2D
• No compression
• 1 image

Related Data and Programs:

The PBMA data page describes the ASCII Portable Bit Map format.

The PGMA data page describes the ASCII Portable Gray Map format.

The PPMB data page describes the binary Portable Pixel Map format.

Reference:

1. the NETPBM homepage.

Routines to create a PPMA file:

• TABLE_BARPLOT_PPMA will read a TABLE file and create a PPMA graphics file representation of the data as a bar plot.
• voronoi_plot takes in a file of points in the unit square and creates a PPMA file of the Voronoi diagram of the points, in any LP norm;

Programs and routines to read a PPMA file:

• MATLAB can read a PPMA file with a command like A=imread('file','PPM').
• ppma_io, a library of C++ routines;
• ppma_io, a library of FORTRAN90 routines;
• ppma_io, a library of MATLAB functions;
• The Visual Toolkit routine vtkPNMReader can read an ASCII PPM file into VTK.

Programs and routines to write a PPMA file:

• The gnuplot command "set terminal pbm color".
• MATLAB can write a PPMA file with a command like imwrite(a,'filename','PPM').
• The Open_GL, graphics display can easily be written to an ASCII PPM file. See the example "gasket_to_ppma.C".
• ppma_io, a library of C++ routines;
• ppma_io, a library of FORTRAN90 routines;
• ppma_io, a library of MATLAB functions;
• The Visual Toolkit routine vtkPNMWriter can write a VTK image to an ASCII PPM file.

Programs to view a PPMA file:

• The AVS module read_any_image can read a PPMA file.
• GIMP, the GNU Image Manipulation Program, can view a PPMA file.
• The Linux program gqview, can view a PPMA file.
• The ImageVision program imgview can display a PPMA file.
• MATLAB can display a PPMA file, once it is read in, with a command like image(A).
• The xv program can view a PPMA file.

Programs to convert a PPMA file to another format:

• cjpeg converts a PPM file to JPEG format.
• The ImageMagick, program convert can convert a PPMA 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 PPMA file and write out a copy in a variety of formats.
• ppma_2_bmp converts a PPMA file to BMP format.
• ppma_2_ppmb converts a PPMA (ASCII) file to PPMB (binary) format.
• xv can read a PPMA file and write out a copy in BMP, FIT, GIF, JPG, PBM, PGM, RGB or TIF format.

Programs to convert a file to PPMA format:

• bmp_2_ppma can convert a BMP file to PPMA 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 PPMA format. However, to force the ASCII format, you must include the switch "-compress none".
• ppmb_2_ppma can convert a PPMB (binary) file to PPMA (ASCII) format.
• djpeg converts a JPEG file to PPM format.
• fig2dev can convert a FIG file to a PPM file by a command like

              fig2dev -L ppm input.fig > output.ppm
            

• GIMP, the GNU Image Manipulation Program, can read a file in a variety of formats, and write it out as a PPMA file.
• xv can read a file in a BMP, FIT, GIF, JPG, PBM, PGM, RGB or TIF format, and write it out as a PPMA file.

Sample PPMA Files:

• blackbuck.ppma, a picture of a buck.
• feep.ppma, a simple example.
• pbmlib.ppma.
• sines.ppma, a kind of bar plot of sine functions, created by BAR_PLOT.
• snail.ppma, a picture of a snail.

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