Friday, March 28, 2014

Why is the BBC blurring images it posts on its website?

 This image of an object in the Indian ocean possibly relating to the missing flight MH370:

was posted today on the BBC's website. It is quite badly blurred. Now, we can easily deblur this image. Using 35 iterations of Richardson–Lucy deconvolution, I obtained this result:


I did some trial and error for the point spread function, one with an exponential decay with a width of 1.2 pixels yielded the best results. Now, there is a suspicious artifact in the lower middle part of the image. This circular white spot with a black dot in the center is blurred in the original image. But when the object and the sea are deblurred, this artifact is also almost perfectly deblurred.

 It could be that the BBC deliberately blurred a sharp image. By putting in a white spot with a dot comprising of a single pixel, the image will contain the exact point spread function needed to deblur the image. Presumably they would normally remove this blurred artifact, but perhaps they forgot to do that in this case.

Now, I did try to use the pixels in the white spot to deblur the image, but that yielded a slightly worse result, presumably because of using a different algorithm. I can't specify the point spread function in the G'Mick plugin that does Richardson–Lucy deconvolution in GIMP, there is a plugin for the ImageJ program that can do deconvolution with an arbitrary point spread function, but only with different methods. The BBC may also have reduced the size of the image after deblurring to make a more precise reconstruction of the original image more difficult.

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