Today I thought I would show how Mad Tea Lab can be used to prototype audio effects in realtime. Note that this only works in Firefox, and that the song might need some time to load.Here is the lab.
Audio streaming support using Mozilla (Audio Data API) was implemented quite a long time ago, but since it’s firefox only and a bit shaky I never felt like documenting it or show it as a feature. But it’s fun and useful so I think it’s about time…
Making an image more (or less) colorful seems like an easy task. But in order to make the colorfulness respond as we expect it to, we need to take human perception into account. A nice way to evalute color-functions is to use gradients that appear to have the same intensity and colorfulness. There is also a sophisticated perceptual model called CIECAM02 that can be used for reference (here is a useful CIECAM02 photoshop plugin). Below is a small tool to compare ways of changing colorfulness. It’s the same source image processed in photoshop using different methods.
Compare for yourself
Hover mouse over the link captions below to compare, click to “lock” an image (hover response might initially be slow due to image loading). You can also compare in high-res.
Overall, this algorithm is a very nice improvement over the older Hue/Saturation dialog, since it seems to be gamma corrected, and calculation is not done in HSV/HSL space*. Result is quite similar to CIECAM02.
Colors are mixed to grey using about 28% 72% 0% (and then interpolated in linear RGB), which is close to perceptual standards.
Bluish images might appear darker after desaturated (and using saturation -100 will discard all blue information).
Saturation values are somewhat counter intuitive, if you saturate by -33 you have to saturate by 50 to get back to the original level. Though it is mathematically correct if you think in percentages; (1 – 0.33) * (1 + 0.5) is about one.
Channel Mixer Dialog
Increasing colorfulness will also increase the perceived brightness of the colorful areas.
Quite smooth and consistent, might be useful if you don’t have access to vibrance color controls.
Mixer values used for grey (+30 +60 +10 Monochrome)
* HSV/HSL color space is strikingly perceptually inconsistent, an extreme example is that it treats these two colors as having the same brightness:
Artifacts from the HSV/HSL transforms can be seen in the comparison tool, such as unsmooth gradients and increased noise (clearly visible in a still image from Canon D7 footage with a high ISO setting). Also note that, for most images these inconsistencies do not pose any major problem.
So it’s Chinese new year, and what animal?
The Rabbit! And what kind of association could
this bring to an oldschool 3D hacker?
Yeah, you got it! Of course it’s the Stanford Bunny!
So this is todays Mad Tea Lab exercise!
Parsing and rendering the good old bun in 3D!
Go try out Mad Tea Lab right away, or check the links to the introducing articles. Feel free to leave general comments and questions under this this post, but also note that you can leave comments on the articles as well!