keithisco, on 19 November 2012 - 09:07 PM, said:
One of images showing UFO/Dead Pixels is quite interesting... I dont currently own Photoshop, but if someone does then I would suggest increasing the Parameters for Pixel Definition (Zoom) to explain what we are looking at. Back in the day, I was on the design team for the Altea Professional Satelite Receiver (originally for Newscorp, later sold to Tandberg Television) and this does not look like any sort of Digital Artefact to me.
If it's the following picture you're talking about, I don't think anybody is seriously suggesting it's "dead pixels".
Here's what you see if you zoom in without applying any smoothing filters.
It's not a digital artefact in itself, but it does contain heavy elements of JPEG artefacting. Hard to know exactly what we're looking at as it's only a handful of pixels across and has been distorted by the JPEG compression process.
The following picture however, is almost certainly dead pixels (note that it has been inversed and then recolorised from the original which had black dots against the sky):
It's easy to simulate it using Photoshop. Put a couple of blank white pixels on a brown gradient background, save it at low JPEG quality, and then resize it upward a bit with bicubic filtering on and you'll get pretty much the same thing. The fact that the same series of images on NASA's website all contain the same 2 little blobs in the exact same place in each picture is further evidence that it's a camera defect of some sort.