Table Of Contents

Differentiation styles

 

 

There are several differentiation visual styles. Currently these styles are based on two algorithms:

Difference

These algorithms compute the mathematical difference between the pixels colours (grouping the components or component by component when Chanel per Chanel is checked).

• when grouping the components (Red/Green/Blue) together, the colour box let you choose which colour must be used for identical pixels, for fully different pixels and those between the threshold (called similar pixels). If you do not specify this colour, similar pixels will be assigned a blended colour between identical and different pixels colours.
  
• when using the Chanel per Chanel option, the difference colours are directly derived from the mathematical difference between the colours components (e.g. black is no difference at all, white difference for all the components)
  

Blank Similar

This algorithm first computes a 50/50 mix of the two images and then blanks out totally the identical pixels and partially similar pixels (with the blanking colour defined in your settings).

In addition to the visual algorithms, Ellié Computing Merge computes the following metrics:

Number of Identical, Similar and Different pixels

The difference amount is defined as the sum of the difference chanel per chanel divided by the number of chanels. Identical pixels are those for which the amount is less or equal to the Exactness threshold. Different pixels are those above the Difference threshold. The Similar pixels are the others.

These numbers are displayed in the status bar as: [exact] < - [similar]~ - > [different].

PSNR (Peak Signal To Noise Ratio) and MSE (Mean Square Error) (optional)

These metrics are often used to determine the quality of an signal treatment. Bitmap images and sounds samples are such signals. The treatment can be for example compression, filtering...

These numbers are displayed in the status bar as: / PSNR=[psnr] MSE=[mse]

See also

• Image Comparisons Options
• Image Colours Options