abzico / libpng_example

Example code demonstrate how to work with libpng

libpng_example

Sample project using libpng to read / write / process png image file in C.

Make sure you have installed libpng on your machine.

Build and Run

Build the project with make, then it will produces test-libpng executable file.

Use make clean to clean generated image files and start over.

How?

See overview image as follow on what to expect.

Program demonstrate the following points

1. Read input fully opaque .png i.e. opaque.png file then use such data to write into .ppm image format for both P3 and P6 (as prove of concept because PPM image format is very easy, and quick to work with to debug and validate pixel data we've read), and as well as .png file.
2. Read input .png with transparency trans.png file then use such data to write into .png file.
3. Generate fully opaque custom image data by setting pixel values then use it to write into .png file.
4. Same as 3 but generate custom image data with transparency.

What Stuff Demonstrated in This Project?

• How to work with libpng to read/write and process (generate by hand) image data to produce .png image
• How to write into .ppm both P3 and P6 format (for purpose of prove of concept reading image data from .png file)

Note

There are 2 input images used and 1 manual operation to generate output image

1. opague.png - program will produce opaque-p3.png, opaque-p6.png, opaque-png.png
2. trans.png - program will produce trans-png.png
3. manual - program will produce manual-png.png and manual-png2.png. The former with full image opaque color, but the latter has edage with size 32 pixels around the image as full transparent leaving the center as opaque color.

PS. Tested on macOS, for Windows, should need a little bit more effort to make a proper build script.

License

MIT, ABZI (abzi.co)