pinch wrote:But, cameras don't do that. They tend toward exposing for the average of the scene, which would underexpose the dress. It has been manipulated.
Really? Are you sure about that?
There's a major reason why many cameras, including cameras in phones, would be designed to try to adjust for centre-field foreground objects by default: most people don't know much about photography, and just point their cameras straight at whatever they're trying to photograph, without knowing they need to do anything about significant differences in foreground and background lighting, but they still want their photos to come out okay. So, cameras that, by default, try to adjust, focus, expose and compensate for centre-field foreground objects, regardless of what's going on in the background round the edges, will tend to satisfy a lot of customers.
In this case, we've got a photo that, it seems, the majority of people initially perceive to be a white and gold dress in relative shadow, illuminated by relatively bluish light, compared to the much more brightly, more yellowy-lit and obviously overexposed background. If the camera treated the dress as poorly-lit when it was brightly-lit - which it could easily do since the dominant foreground object actually is quite a lot darker than most of the background - and if the camera white-balanced for relatively blue illuminating light - which it could easily do since the dominant foreground object actually is very blue, unlike most of the background - then you'd get the dress overexposed and wrongly white-balanced in such a way that it looks lighter and less blue than it actually is, but without necessarily looking to everyone like it was overexposed or wrongly white-balanced.
Your hypothesis that someone did a bad job of trying to lighten the original photo, by changing the gamma, to produce the photo that the world has now seen, doesn't really explain anything that isn't already explained without anyone having to change the gamma. I don't think it's a terribly likely hypothesis, and I don't think it works very well.
If the gamma corrected image looks too dark to you, then consider that you may be viewing it on a low gamma display or bright environment.
When I said, "it's got that 'underexposed' kind of look to it," I meant I could see why you could conclude the original image was underexposed. It had that murky, details-getting-lost-in-murk kind of look to it.
As for my display's gamma, if it was too low, then I'd either routinely find images appearing "too dark", or I'd be used to it, and wouldn't find your "gamma corrected" image "too dark". Either way, I wouldn't find your "gamma corrected" image remarkably different to most other images I see on my display.
Try correcting with gamma around 2, and you will see a milder but accurate rendition: The dress is in a shop that's probably lit by CFL lamps, but the overhead light is incandescent (black becoming gold when boosted) and the background out the window is daylight.
Where did you learn about it being in a shop? I'm really not sure the scene is as you describe it.
The human visual system is amazing, but it can be hoodwinked.
Yes, I think there's a bit of irony there.
In your earlier post, you mentioned your patent, as if that was evidence of expertise or authority. Unfortunately, there are plenty who aren't nearly the experts they think they are who cite their patents as if those patents mean a lot more than they actually do. There have been plenty of cranks and crackpots who have expected others to bow to their supposed superiority on the basis of such patents. I take such 'evidence' of 'expertise' as a little warning flag instead.
So, oh expert, please tell me what's wrong with the following:-
"To correctly reduce the resolution of an ordinary, greyscale image, it's necessary to slightly blur the image first, so as to avoid visible artefacts of resolution reduction. Otherwise, when blocks of pixels are averaged together into single, lower-resolution pixels, artefacts will often be produced, such as sharp edges that are close to vertical and horizontal getting a sort of stair-stepped effect. Blurring the image first with a simple filter, so as to remove details at scales similar to or smaller than the new, lower-resolution pixels, will avoid such artefacts."
Please also tell me a correct method for reducing the resolution of such images, and please explain why it's correct.
I am male, I am 'him'.