enlighten's Introduction

Enlighten

Automatically brighten dark areas in high dynamic range images

This code shows how to automatically brighten the darker areas of high dynamic range images.

To compile (tested on macOS and Ubuntu) just type

% make

To test it

% make test

This image processing method is related to Homomorphic Image Processing but avoids the use of log space processing.

Homomorphic Filtering - wikipedia

Homomorphic Filtering - faadooengineers

This method is used in my photo painting app for iOS called "PhotoViva"

The image blurring is implemented by resizing an image to a small size and then resizing it big again.

This process can be implemented in OpenGL using shaders to automatically correct rendered images in real-time.

Enlighten sees images like your eyes see the world.

Credits: Uses https://github.com/nothings/stb to read, write and resize images.

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enlighten's Issues

error compilation on Ubuntu 20.04.6 LTS

error compilation on Ubuntu 20.04.6 LTS using Makefile

make                                                                     
cc enlighten.c -o enlighten
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbi__ldr_to_hdr':
enlighten.c:(.text+0x2cc6): undefined reference to `pow'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbi__hdr_to_ldr':
enlighten.c:(.text+0x2e8c): undefined reference to `pow'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__srgb_to_linear':
enlighten.c:(.text+0x20c81): undefined reference to `pow'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__linear_to_srgb':
enlighten.c:(.text+0x20ccb): undefined reference to `pow'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__get_filter_pixel_width':
enlighten.c:(.text+0x212de): undefined reference to `ceil'
/usr/bin/ld: enlighten.c:(.text+0x21314): undefined reference to `ceil'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__get_coefficient_width':
enlighten.c:(.text+0x2139f): undefined reference to `ceil'
/usr/bin/ld: enlighten.c:(.text+0x213d0): undefined reference to `ceil'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__calculate_sample_range_upsample':
enlighten.c:(.text+0x21723): undefined reference to `floor'
/usr/bin/ld: enlighten.c:(.text+0x21743): undefined reference to `floor'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__calculate_sample_range_downsample':
enlighten.c:(.text+0x21803): undefined reference to `floor'
/usr/bin/ld: enlighten.c:(.text+0x21823): undefined reference to `floor'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__calculate_coefficients_upsample':
enlighten.c:(.text+0x2189a): undefined reference to `ceil'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `stbir__calculate_coefficients_downsample':
enlighten.c:(.text+0x21b6a): undefined reference to `ceil'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `canvas_diameter':
enlighten.c:(.text+0x28086): undefined reference to `sqrt'
/usr/bin/ld: /tmp/ccpnvA0K.o: in function `canvas_blur':
enlighten.c:(.text+0x28156): undefined reference to `round'
/usr/bin/ld: enlighten.c:(.text+0x28176): undefined reference to `round'
collect2: error: ld returned 1 exit status
make: *** [Makefile:2: all] Error 1