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PNG2 format (png2)

2D depiction of a single molecule as a .png file

The PNG2 format is used ‘behind the scenes’ by the PNG format if generating image files, and the best way to use it is actually through the PNG format. While it possible to generate a .png file directly using the PNG2 format as follows...:

obabel -:"CC(=O)Cl" -opng2 -O mymol.png

...it is much better to generate it using the PNG format as this allows you to embed a chemical structure in the .png file header which you can later extract:

$ obabel -:"CC(=O)Cl" -O mymol.png -xO smi
$ obabel mymol.png -osmi
CC(=O)Cl

The PNG2 format uses the Cairo library to generate the .png files. If Cairo was not found when Open Babel was compiled, then this format will be unavailable. However, it will still be possible to use the PNG format to read .png files if they contain embedded information.

Note

This is a write-only format.

Write Options

p <pixels> image size, default 300