Awesome

PNGenc

Copyright (c) 2021 BitBank Software, Inc.<br> Written by Larry Bank<br> bitbank@pobox.com<br>

What is it?

An 'embedded-friendly' (aka Arduino) PNG image encoding library<br> <br>

Why did you write it?

Starting in the late 80's I wrote my own imaging codecs for the existing standards (CCITT G3/G4 was the first). I soon added GIF, JPEG and not long after that, the PNG specification was ratified. All of this code was "clean room" - written just from the specification. I used my imaging library in many projects and products over the years and recently decided that some of my codecs could get a new lease on life as open source, embedded-friendly libraries for microcontrollers.<br> <br>

What's special about it?<br>

The PNG image specification was written at a time when computers had megabytes of RAM and conserving memory wasn't a big priority. The memory allocated for encoding the compressed data (zlib) and for holding the uncompressed image can be quite a bit more than is available on modern microcontrollers (usually measured in K bytes). Three goals for this project are: easy to compile+use on all embedded systems, use a minimal amount of RAM and be self-contained. One of the dependencies I like to remove when working on embedded software is malloc/free. When compiling on a system with a tiny amount of RAM, heap memory management might not even exist.<br>

Feature summary:<br> ----------------<br>

• Runs on any MCU with at least 45K of free RAM<br>
• No external dependencies (including malloc/free)<br>
• Encode an image line by line<br>
• Allows encoding pixels of type grayscale, indexed, truecolor or truecolor+alpha
• Supports up to 8-bits per color stimulus<br>
• Allows defining a transparent color or alpha palette values<br>
• Allows control of the zlib compression effort amount (1-9)
• Arduino-style C++ library class with simple API<br>
• Can by built as straight C as well<br> <br>

How fast is it?<br> ---------------<br> The examples folder contains a sketch to measure the performance of encoding a 128x128 image generated dynamically.<br>

Documentation:<br> ---------------<br> Detailed information about the API is in the Wiki<br> See the examples folder for easy starting points<br> <br>