For those watching in black and white...

[DBT]

The coloured lines are not as sharp as they could be, but it is a black and white photo.

For fuck's sake, I posted pixel RGB content, it's not black and white photo, Even hair is not black.

There is no brain effect here at all. Brain does not paint anything Color vision has less sensitivity and resolution than black-white. So at sufficient distance or off center view you simply can not resolve color features, it all becomes solid color

There is a fair bit of 'leeching out' of the coloured lines, but the central patches within the squares are shades of grey. You can see it in the blow ups. It's the leeching that gives the impression of colour, in some cases as much leeching as there is grey scale. It's neither entirely coloured or grey scale. It only work when the squares are small.

 

[bigfield]

Here's another scattershot attempt to recreate the illusion, based on the "blue" shirt to the right of the picture.

The photo really is black and white: I sampled the picture, checked the HSL values, and found that the greys really are grey.

However, the coloured lines are actually very thick: I'd say that more than 50% of the picture's area is coloured, even in the higher-res version skepticalbip found.

Anyway, see if any of these actually look blue-grey, rather than grey-with-blue-lines.

I attempted to minimise contrast to trick the eyes into ignoring the grid pattern, but it's going to look wildly different depending on your screen quality, settings and viewing angle.

(Also, I'm slightly deficient in blue-yellow colour vision, so this was probably a stupid choice.)

If I stand two metres away from the monitor, some of the lighter grey squares look blue-grey, with or without blur. So I think this illusion does work, but it's critical that there is no contrast between the colour lines and the grey background.

 

[barbos]

The coloured lines are not as sharp as they could be, but it is a black and white photo.

For fuck's sake, I posted pixel RGB content, it's not black and white photo, Even hair is not black.

There is no brain effect here at all. Brain does not paint anything Color vision has less sensitivity and resolution than black-white. So at sufficient distance or off center view you simply can not resolve color features, it all becomes solid color

There is a fair bit of 'leeching out' of the coloured lines, but the central patches within the squares are shades of grey. You can see it in the blow ups. It's the leeching that gives the impression of colour, in some cases as much leeching as there is grey scale. It's neither entirely coloured or grey scale. It only work when the squares are small.

There is a lot of leeching, so much so that in some cases it's basically whole thing gets colored. And then there is a problem of black hair which is not shade of gray but shades of red. Image was never converted to black-and white.
The whole thing is BS

 

[DBT]

There is a fair bit of 'leeching out' of the coloured lines, but the central patches within the squares are shades of grey. You can see it in the blow ups. It's the leeching that gives the impression of colour, in some cases as much leeching as there is grey scale. It's neither entirely coloured or grey scale. It only work when the squares are small.

There is a lot of leeching, so much so that in some cases it's basically whole thing gets colored. And then there is a problem of black hair which is not shade of gray but shades of red. Image was never converted to black-and white.
The whole thing is BS

Seems so. The designer should have taken more care.

 

[DBT]

Perhaps some better illusions;

''This is pretty trippy. Dark dots rapidly appear and disappear at the intersections. However, if you stare at one intersection, the crossroad remains white.''

 

[Jimmy Higgins]

Here's another scattershot attempt to recreate the illusion, based on the "blue" shirt to the right of the picture.

The photo really is black and white: I sampled the picture, checked the HSL values, and found that the greys really are grey.

However, the coloured lines are actually very thick: I'd say that more than 50% of the picture's area is coloured, even in the higher-res version skepticalbip found.

Anyway, see if any of these actually look blue-grey, rather than grey-with-blue-lines.

I attempted to minimise contrast to trick the eyes into ignoring the grid pattern, but it's going to look wildly different depending on your screen quality, settings and viewing angle.

(Also, I'm slightly deficient in blue-yellow colour vision, so this was probably a stupid choice.)

If I stand two metres away from the monitor, some of the lighter grey squares look blue-grey, with or without blur. So I think this illusion does work, but it's critical that there is no contrast between the colour lines and the grey background.

This was the reason for my question. You are trying to create an illusion on a gray color. The image contains different shades of gray, that might have some visual component to the color they actually represent. I was curious if that image could switch the colors of the shirts, or whether the shade of gray was fixed to a particular color (ie, can the green grid have the same effect on the shirt with the blue grid.

 

[Gun Nut]

There is no illusion, photo is actually color.

It's really not.

If you zoom in, you can see that there's a grid of coloured lines, and the picture beneath them is greyscale monochrome.

well, if I "zoom in" to this post, all there is is a bunch of black and white dots... no actual words.
All color is on a digital picture is a mixture of colored dots. If you draw colored dots (or connected colored dots as in a colored line) over a black and white picture, you get a colored picture. Take a crayon and do the same thing with any black and white picture. Your kids do it all the time with coloring books. That the space between dots has greyscale tones is irrelevant to the fact that someone applied color to it. This is as much an optical illusion as are these words on the page, made up of little black dots.

 

[bigfield]

Here's another scattershot attempt to recreate the illusion, based on the "blue" shirt to the right of the picture.

The photo really is black and white: I sampled the picture, checked the HSL values, and found that the greys really are grey.

However, the coloured lines are actually very thick: I'd say that more than 50% of the picture's area is coloured, even in the higher-res version skepticalbip found.

Anyway, see if any of these actually look blue-grey, rather than grey-with-blue-lines.

I attempted to minimise contrast to trick the eyes into ignoring the grid pattern, but it's going to look wildly different depending on your screen quality, settings and viewing angle.

(Also, I'm slightly deficient in blue-yellow colour vision, so this was probably a stupid choice.)

If I stand two metres away from the monitor, some of the lighter grey squares look blue-grey, with or without blur. So I think this illusion does work, but it's critical that there is no contrast between the colour lines and the grey background.

This was the reason for my question. You are trying to create an illusion on a gray color. The image contains different shades of gray, that might have some visual component to the color they actually represent. I was curious if that image could switch the colors of the shirts, or whether the shade of gray was fixed to a particular color (ie, can the green grid have the same effect on the shirt with the blue grid.

I think the lightness value of the grey and the coloured grid need to be close so that your eye doesn't really register the grid, but otherwise I think it's independent of the colour's hue.

 

[bilby]

There is no illusion, photo is actually color.

It's really not.

If you zoom in, you can see that there's a grid of coloured lines, and the picture beneath them is greyscale monochrome.

well, if I "zoom in" to this post, all there is is a bunch of black and white dots... no actual words.
All color is on a digital picture is a mixture of colored dots. If you draw colored dots (or connected colored dots as in a colored line) over a black and white picture, you get a colored picture. Take a crayon and do the same thing with any black and white picture. Your kids do it all the time with coloring books. That the space between dots has greyscale tones is irrelevant to the fact that someone applied color to it. This is as much an optical illusion as are these words on the page, made up of little black dots.

You appear to think that you are arguing against the clear fact that these are optical illusions, by giving examples of how they are simply optical illusions.

I don't find that argument at all compelling.

 

[Gun Nut]

well, if I "zoom in" to this post, all there is is a bunch of black and white dots... no actual words.
All color is on a digital picture is a mixture of colored dots. If you draw colored dots (or connected colored dots as in a colored line) over a black and white picture, you get a colored picture. Take a crayon and do the same thing with any black and white picture. Your kids do it all the time with coloring books. That the space between dots has greyscale tones is irrelevant to the fact that someone applied color to it. This is as much an optical illusion as are these words on the page, made up of little black dots.

You appear to think that you are arguing against the clear fact that these are optical illusions, by giving examples of how they are simply optical illusions.

I don't find that argument at all compelling.

It's not an "illusion" that we cannot see in the dark. It is not an "illusion" that we cannot identify the face of a person 2 miles away. It is not an "illusion" that 2 yellow dots mingled with 2 red dots resolves to the eye as a contiguous orange spot. That is how color is resolved by the eye.
To say... "well, that's an illusion because there is no orange".. then I say there is no spoon... there is no "solid"; everything has massive amounts of space between its atoms. There is no color, just wavelengths of light... getting silly.

 

[Gun Nut]

An illusion is (As Tyson put it), a "brain failure". Seeing colors that have been placed there so close together as to not be capable of seeing the space in between them is not a brain failure.
That basic, most common, optical illusion with two equal length parallel lines that look to be different lengths because of differnt arrowheads on them (forward facing and inverted.. inverted one looking smaller), is an optical illusion. Drawing those two lines one on top of each other and removing the arrow heads such that they are essentially one line, is not.

 

[bilby]

well, if I "zoom in" to this post, all there is is a bunch of black and white dots... no actual words.
All color is on a digital picture is a mixture of colored dots. If you draw colored dots (or connected colored dots as in a colored line) over a black and white picture, you get a colored picture. Take a crayon and do the same thing with any black and white picture. Your kids do it all the time with coloring books. That the space between dots has greyscale tones is irrelevant to the fact that someone applied color to it. This is as much an optical illusion as are these words on the page, made up of little black dots.

You appear to think that you are arguing against the clear fact that these are optical illusions, by giving examples of how they are simply optical illusions.

I don't find that argument at all compelling.

It's not an "illusion" that we cannot see in the dark. It is not an "illusion" that we cannot identify the face of a person 2 miles away. It is not an "illusion" that 2 yellow dots mingled with 2 red dots resolves to the eye as a contiguous orange spot. That is how color is resolved by the eye.
To say... "well, that's an illusion because there is no orange".. then I say there is no spoon... there is no "solid"; everything has massive amounts of space between its atoms. There is no color, just wavelengths of light... getting silly.

Congratulations. You have correctly concluded that reality is silly.

Now, if you can make that last, tiny, logical leap to the conclusion that humans almost invariably categorise things in a way that is arbitrary and owes nothing to reality, you will have learned two valuable lessons. If you can squash your ego to the extent of including yourself in that conclusion, maybe even three.