In a rather curious case of confused identify, a photo of a piece of fruit changes itself based on what browser it is displayed it. What’s the secret behind the optical illusion? Is it a pear, an apple, or both?

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问题

超级用户读取器Ethree写入：

Check this image out:

On Chrome and Firefox it will show as a pear. Now, try to save it and look at it saved on your desktop. Also, try viewing in safari or IE. It will display as an apple!

Try clicking the image and moving it around, you will notice the apple appears.

I guess my question will be, “why does this happen?”

为什么呢？我们在Chrome中看到它是一个梨，当我们将它保存到下载文件夹时，它显示为一个苹果。

答案

超级用户贡献者Matthew提供了对视错觉的洞察：

The “white” pixels in the apple picture contain the picture of a pear, stored at a much higher intensity, i.e. very bright.

The “black” pixels in the pear picture contain the picture of an apple, stored at a fairly normal intensity, but scaled down to near black with the gamma correction.

The image contains a gAMA chunk specifying a file gamma value of 0.02. When displayed without gamma correction, the viewer sees an apple with “white” pixels interspersed, which are actually the pear at its original (high) intensity.

When displayed with gamma correction, the viewer sees a colour-corrected pear with “black” pixels which are actually the apple rendered at a much lower gamma value.

Browsers which display the pear are showing the image using the gamma information provided in it, while browsers which display the apple are not using this gamma information.

换句话说，Chrome尊重gamma校正值，而internetexplorer不尊重。

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