# Some small (but useful) applications

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The program contained in this package are protected by the
GPL license.

**One implementation of DERICHE algorithm adapted to color images**

Deriche

**An algorithm which allows you to visualize 3D histograms of color images**

This program was originally designed by Patrick Moreau

Cube

**An algorithm which computes the mean squared error (in a given color space) between two images**

EQM

** The union-find algorithm : An example of implementation** (see function region_oracle in file region to modify the segmentation criterion, The one proposed is quite simple).

Union-find

** A quantization algorithm which allows you to simulate any top-down quantization algorithm using fixed axis.
**

Fixed axis

** A quantization algorithm which allows you to simulate any top-down quantization algorithm using major axis.
**

Major axis

** An implementation of Xiang97 bottom-up quantization algorithm.
**

Xiang

** An implementation of the inverse colormap algorithms of:**

** An implementation of the trivial inverse colormap algorithm using the following heuristics :**
- Brute force computation of all distances
- Norm L alpha instead of L2
- Partial sum
- A sort of the colors in the colormap.
- Improvement with the computation of inner distances within the colomap.
- Improvement with an hash table.

Click Here to download.

You have below the execution times in seconds of these heuristics on a Pentium II 350Mz, with the Lenna test image (480x512) and colormaps with increasing sizes (16 colors to 512). Note that the trivial algorithm (without any optimisation) is not always the worse one.

** An algorithm to compare color images:**
- Criteria designed by Alain Tremeau
- implementation performed by Gabriel Bouvigne under my responsability
- Image library implemented by Philippe Vautrot and Laurent Hussenet (with the collaboration of Gabriel Bouvigne)

Click Here to download

** A quantization algorithm based on a split and merge approach with the first Inverse colormap algorithm (presented to CGIP:)**
Click Here to download

** A quantization algorithm based on a split and merge approach (with the second inverse colormap algorithm (presented to CGIP:)**
Click Here to download

Luc Brun