📚 Resume

This is a full Modern C++ Object Oriented library for PNG file format Encoder/Decoder.
This library designed to be tiny as possible, purpose severals functions that make easier Pixels Manipulations inside PNG images.

💡 Idea

...Some day, I was looking for a structured PNG library written in C++ for my project. but I could not find anything simple enough, lightweight and Modern. Everything what I tried required 'old c methods' to integrate or had some limitations or was too heavy. I wanted something powerfull and small enough, following new coding 'standards'.
This was the reason why I decided to write this Encoder/Decoder, which no need to manipulate directly memory, with OOP and exceptions features.

🛠️ Features

• full OOP paradigm
• Exceptions Handling
• multiple IDAT chunks
• auto-detect endianess
• PHYS additionnal chunk
• CRC32 computing algortithm
• Hardware-independent processing
• compress ratio option for encode
• Simple and double bit Depths (8 & 16)
• Partial Parsing(rapid informations retrieve)
• Various colors modes (grayscale, grayscale alpha, RGB, RGBA)
• MultiThreading dynamic scanline filtering(better time-size compress ratio)

⚙️ Building

Makefile and Windows compiling files are provided, just copy src and includes files in your project folder.
This project use zlib, so to avoid using dll is to directly include zlib source into your project.

🏴󠁶󠁥󠁷󠁿 Dependencies

zlib 1.2.3

📈 Performance

Here down is a graph that show efficiency of the multithread dynamic scanline filtering method.
A set of 512 images was used to generate this graph,
Where each image is a downscaled version of an initial image, to make this repeatable

Script for image downscale:

from PIL import Image

for i in range(1, 512 + 1, 1): 
    basewidth = 10*i
    img = Image.open('red.png')
    wpercent = (basewidth/float(img.size[0]))
    hsize = int((float(img.size[1])*float(wpercent)))
    img = img.resize((basewidth,hsize), Image.Resampling.LANCZOS)
    img.save("./out/{:.1f}".format(i) + ".png")

Build on :

Intel(R) Core(TM) i7-4810MQ CPU @ 2.80GHz (8 CPUs), ~2.8GHz
Memory: 16384MB RAM DDR4
WDC WD5000LPCX-24C6HT0 SATA 500GB
Windows 10 Professionnel 64-bit (10.0, Build 18362)
GNU GCC Compiler Multilib