PNG Files
Portable Network Graphics

These are some examples of PNG files. "PNG" stands for "Portable Network Graphics".

PNG files can do a good job of showing both line graphics (what PostScript files do best), and bit-mapped graphics (which are commonly handled by JPEG or GIF files). Most web browsers support the PNG format, which makes it easy to include pictures directly in a web page.

1. The PNG Home Page at http://www.libpng.org./pub/png/
2. David Duce, editor,
   Portable Network Graphics (PNG) Specification, Second Edition.
   Technical Report REC-PNG-20031110,
   World Wide Web Consortium, 2003.
3. Greg Roelofs,
   PNG: The Definitive Guide,
   O'Reilly, 1999,
   ISBN: 1-56592-542-4,
   LC: T385.R588.

Programs to create a PNG file:

• The gnuplot command "set terminal png".

Programs and routines to read a PNG file include:

• MATLAB can read a PNG file with a command like A=imread('file','PNG').

Programs and routines to write a PNG file:

• MATHEMATICA includes an Export[filename,object] command that can save a graphics object as a PNG file.
• MATLAB can write a PNG file with commands like

  
              IM(:,:,1) = red data;
              IM(:,:,2) = green data;
              IM(:,:,3) = blue data;
              imwrite ( IM, 'file.png', 'PNG' )
            

  .

  
              [ X, map ] = capture ( figure_handle );
              imwrite ( X, map, 'file.png', 'PNG' )
            

  .

Programs to display a PNG file:

• Microsoft Internet Explorer can display a PNG file.
• The Linux program gqview, can view a PNG file.
• ImageMagick can display a PNG file.
• The ImageVision program imgview can display a PNG file.
• MATLAB can display a PNG file, once it is read in, with a command like image(A).
• The Netscape program can display a PNG file.
• QuickTime or QuickTime Player can display a PNG file.
• Microsoft WORD can display a PNG file.

Programs to convert a PNG file to another format:

• Adobe Acrobat Professional can read a PNG file and convert it to PDF format.
• The ImageMagick, program convert can convert a PNG file to BMP, CGM, EPS, FIG, FITS, GIF, JPG, PBM, PDF, PGM, PNM, PPM, PS, RGB, TIF, XBM or XPM format.
• PNGTOPNM, a NETPBM program, can convert a PNG file to a PNM file.

Programs to convert a file to PNG format:

• The ImageMagick, program convert can convert a BMP, CGM, EPS, FIG, FITS, GIF, JPG, PBM, PDF, PGM, PNM, PPM, PS, RGB, TIF, XBM or XPM file to PNG format.
• fig2dev can convert a FIG file to a PNG file by a command like

              fig2dev -L png input.fig > output.png
            

• The ghostscript program can convert a PS file to PNG format.
• The NETPBM program pnmtopng can convert a PNM file to a PNG file.
• tiff2png can convert a TIFF file to a PNG file.

Sample Files:

• all_gray.png, a tiny monochrome image;
• aquarium.png, a model of Greg Hood's new surf aquarium;
• bar.png;
• bell_206.png, the Bell 206 helicopter;
• bell_v22.png, the Boeing-Bell V22 Osprey;
• blackbuck.png, an image of a deer;
• bmp_08.png, a monochrome image derived from a BMP file;
• bmp_24.png, a three-color image derived from a BMP file;
• dots.png, dots all I can say;
• football_seal.png, the seal of Football Stadium University;
• heawood.png, an image of the Heawood graph, converted from a GRF file to an EPS file by GRF_TO_EPS, converted to a PNG file by ImageMagick Convert.
• humanoid_tri.png, a 2D 'snapshot' of a 3D humanoid shape made with 96 triangular faces.
• knightstour.png, an image of the Knight's Tour graph, converted from a GRF file to an EPS file by GRF_TO_EPS, converted to a PNG file by ImageMagick Convert.
• move1.png, an optical illusion in which dots seem to move;
• move2.png, an optical illusion in which dots seem to move;
• move3.png, an optical illusion in which dots seem to move;
• pengbrew.png, a penguin with a beer;
• petersen.png, an image of the Petersen graph, converted from a GRF file to an EPS file by GRF_TO_EPS, converted to a PNG file by ImageMagick Convert.
• pngnow.png;
• pngtest.png, a picture of the stylized letters "PNG";
• scs_logo.png, the logo for the School of Computational Science.
• sines.png, a kind of bar plot of sine functions, created by BAR_PLOT.
• snail.png, a snail;
• tiler_3d.png, an image of the 3D pattern made by TILER_3D.
• tutte.png, an image of the Tutte graph, converted from a GRF file to an EPS file by GRF_TO_EPS, converted to a PNG file by ImageMagick Convert.
• vt_logo.png, a circular logo for Virginia Tech.
• vt2_logo.png, a rectangular logo for Virginia Tech.

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