An image processing library implemented in pure-C

About

Ocular is a library for common and advanced image processing algorithms, without the use of any external dependencies. Suggestions for new features are welcome.

Note: Big-Endian RGBA byte-order is expected for all pixel data.

Documentation

The documentation of the exported functions can be found at Library Documentation.

Features

Color Adjustment Filters

• Grayscale
• RGB
• HSL
• Average Luminance Threshold
• Color matrix
• Sepia
• Chroma Key
• Lookup (remap colors)
• Saturation
• Gamma
• Brightness/Contrast
• Exposure
• False color (mix between two colors using luminance)
• Haze (add/remove)
• Opacity
• Levels (like Photoshop)
• Hue
• Highlight/Shadow/Tint
• Highlight/Shadow
• Monochrome
• Color Invert
• Luminance Threshold (similar to Photoshop Threshold filter)
• White Balance
• Vibrance
• Skin Tone
• Auto Contrast
• Auto Gamma Correction
• Auto Level
• Auto White Balance
• Equalize (like Photoshop)
• Auto Threshold (with 13 methods)
• Backlight Repair (corrects extremely low or non-uniform lighting)
• Image Blending (supports 27 Photoshop modes)

Image Processing Filters

• 2D Convolution
• Bilateral (selectively blurs preserving edges and other details)
• Average (Mean) Blur
• Gaussian Blur
• Box Blur
• Motion Blur
• Median Blur
• Erode/Dilate
• Radial Blur
• Surface Blur
• Unsharp Mask
• Sharpen
• Lanczos resampling (resize)
• Canny Edge Detect
• Gradient Edge Detect
• Sobel Edge Detect
• Deskewing
• Pixelate (Mosaic)
• Oil Paint

General

• Retrieve average image luminosity
• Retrieve average color
• Retrieve image size
• Crop
• Flip (Vertical/Horizontal)
• Bilinear image rotation
• Hough transform line detection

Color Space Conversion

Note: These are primarly used for included filters and added on as needed basis.

• RGB <--> YIQ
• RGB <--> HSL
• RGB <--> HSV
• RGB <--> YCbCr

Running

To compile the library, simply do the following:

cmake .
make

This will out the following 3 files:

• static library lib\libocular.xxx
• dynamic link library bin\ocular.dll
• console demo bin\demo.exe

TODO

GUI Demo Application

I'm working on a full-featured image viewer app in C# for showing-casing library features using the compiled DLL.

Library

I have a very long list of features to implement, some advanced features include:

retinex, automatic red-eye removal, skin smoothing and possibly deblurring.