June 11th, 2010 - We may have a plan…
We have developed a sketch model for determining colour accuracy based on a calculation of the distance between two points in lab colour space (CIELAB). In lab space, colour is mapped as a point on a 3-dimensional Cartesian plane. In order to determine accuracy of colour reproduction we have decided to pre-determine our colour space as indexed colour (only using a set number of specific colours) with a 6-bit per pixel colour space (64 colours).
Once we map these colours onto the lab space, we use the following formula D= √((L₁-L₂)² + (a₁-a₂)²+(b₁-b₂)²)) to calculate the distance between the colours. The complication here is that each pixel will have to run this equation 64 times (assuming 6-bit per pixel) to determine which of our indexed colours is closest (distance in CIELAB 3d space) and then replace the original colour with its’ closest approximation yielding something like the image below.Many of the colours will have visual relationships and approximate the colours we have selected, but others may have a less corollary visual relationship.
If you want to get a visual representation of CIELAB space beyond the screen shots below, download PerfX 3D Gamut Viewer.
We have yet to run any tests on this beyond using indexed colour to limit a palette. Potential problems could include:
1. sRGB to CIELAB conversions to bring webcam data into a usable form.
2. Computational efficiency (which we are working on).
3. Visual relationships between mapped colours and their perceptual counterparts may be aesthetically complicated.
Below: Ryan in 256 Colours, Screen Shots of CIELAB Space.
