Can you see me ?

[Karlos]

I had no problem with either one. The first was screamingly obvious but the secoond was a bit more subtle.

: Again, the interesting thing to note here is that folks who are colorblind
: are not 'impaired' in the sense that they really see *less* than others,
: rather, you could just say that they're more sensitive to some things
: than the rest of us are.

Quite! I challenge any "normal" to be more perceptive of the blue end of the spectrum than me ;-)

*cough* Where's my evil antipodean sidekick with those fusion crackers?

[Karlos]

One day I thought long and hard about colour perception and wrote an image filter to try and show people with normal vision how I perceive the world.

It isn't perfect - I can usually distinguish a colour (anything strongly saturated at least) from a non colour (ie grey or very unsaturated colours) but aside from blues and some greens I really can't differentiate them from each other.

Secondly, my blue perception is considerably stronger than normal. Blues appear more vivid and varied to me than to someone with normal vision, so much so that I tend to see colours that have any significant blue hue in them as blue even when they could be some bluish shade of green, for instance.

The filter analyses the hue of every pixel in the source image, based on a self made hue/brightness calibration test (where I matched about 30 points in the spectrum to a greyscale brightness) and reshades the non blue colours to grey, passing only the minimum amount of green I can differentiate (probably not that accurately though). Secondly, it enhances the blue tones, pulling some of the non-blue tones back towards blue in line with the calibration.

All of this was compounded by my CRT's spectral curve so its hardly accurate. However, it might give you some idea:

blue flowers

blue flowers - filtered

The second image tends to filter out the sky which in reality looks quite blue to me also, but the filter was probably more than overworked by the flowers ;-)

The point is not so much that everything looks grey to me, as I said, it's more that it is impossible to tell the vast majority of different non-blue colours apart. I haven't found a better way to render this other than simply removing the hue information to give normal sighted people the same perception.

PS:If you get a 403, just enter the url into the address bar directly ;-)

[Karlos]

Vincent wrote:
Erm... both pictures are the same ;-)

Gotcha!

No, seriously... check again, I pasted the url twice by accident ;-)

[Karlos]

cecilia wrote:

is that the intention?

It's only an approximation.

The intention is to dramatically reduce the ability to distinguish the non-blue colours apart and enhance the differences in blue hues making them more distinct than in the original image.

The grey thing is the only way I thought that I could make the hues indistinguishable to normal sighted people. However, in reality I can distinguish strong saturated colours from unsaturated colours/greys, I just cant tell them apart from each other other than their overall brightness.