Amiga.org

Coffee House => Coffee House Boards => CH / Entertainment => Topic started by: The_Editor on June 28, 2006, 04:21:00 PM

Title: Can you see me ?
Post by: The_Editor on June 28, 2006, 04:21:00 PM

Little test to see if your "Normal" or not

hehe


http://3cag.net/forum/viewtopic.php?t=63
Title: Re: Can you see me ?
Post by: Vincent on June 28, 2006, 08:19:01 PM
Not looking directly at the first pic, I could see the bottom right of the hidden image.

Could see bugger all when looking at it though.

Couldn't see anything at all in the bottom one.
Title: Re: Can you see me ?
Post by: on June 28, 2006, 08:49:37 PM
On my TFT at work, I could clearly make out both.

On the CRT here at home, I could only make out the second one.
Title: Re: Can you see me ?
Post by: Karlos on July 08, 2006, 04:05:49 PM
I had no problem with either one. The first was screamingly obvious but the secoond was a bit more subtle.

Quote
: 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?
Title: Re: Can you see me ?
Post by: metalman on July 09, 2006, 06:16:38 AM
Interesting!
Viewed images on CRT

Could identify the image on Red Spectrum Gradient Test, it stood out on the Lower right, much harder to see in the top left bright red area.

On the Red Speckles Test, Nothing.
Title: Re: Can you see me ?
Post by: Karlos on July 09, 2006, 01:12:21 PM
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 (http://www.extropia.co.uk/img/blueflowers.jpg)

blue flowers - filtered (http://www.extropia.co.uk/img/blueflowers_k.jpg)

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 ;-)
Title: Re: Can you see me ?
Post by: Vincent on July 09, 2006, 02:06:07 PM
Erm... both pictures are the same ;-)
Title: Re: Can you see me ?
Post by: Karlos on July 09, 2006, 02:10:47 PM
Quote

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

Gotcha!

No, seriously... check again, I pasted the url twice by accident ;-)
Title: Re: Can you see me ?
Post by: cecilia on July 09, 2006, 06:23:55 PM
the second pic has basically desaturated the green tones (making them look greyish).
the flowers are still blue.

is that the intention?
Title: Re: Can you see me ?
Post by: Karlos on July 09, 2006, 09:36:03 PM
Quote

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.
Title: Re: Can you see me ?
Post by: metalman on July 10, 2006, 05:48:09 AM
Color and Optical Illusions (http://www.colorcube.com/illusions/illusion.htm)

64 Optical Illusions & Visual Phenomena (http://www.michaelbach.de/ot/)