MSL Images & Cameras, technical discussions of images, image processing and cameras |
MSL Images & Cameras, technical discussions of images, image processing and cameras |
Aug 16 2012, 11:05 PM
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Senior Member Group: Members Posts: 2228 Joined: 1-December 04 From: Marble Falls, Texas, USA Member No.: 116 |
I'm still trying to figure out a number of things about the new images we are trying to work with. Assuming others are likewise trying to learn, I thought I would open this thread to create a place for such discussions.
I'd like to start out with a comment about raw image contrast. There have been several postings in the main threads about whether or not the MSL raw images have been stretched like those from the MER missions. I am certainly no expert on this, but it looks to me as if the MSL images have not been stretched at all. I haven't tried to analyze all of the image types, but the hazcams and navcams have pixel brightness histograms that are very different from their MER counterparts. This attached image compares MER and MSL navcams along with their luminosity histograms. The MSL images clearly are not using the entire, available range of brightness values, whereas the MER raws do. For this reason, the MSL raw images can usually be nicely enhanced by simply stretching the distribution of brightness across the full 256 value range. -------------------- ...Tom
I'm not a Space Fan, I'm a Space Exploration Enthusiast. |
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Aug 17 2012, 02:52 PM
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Senior Member Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 |
I've noticed the same thing. It means for some of these images, we're effectively getting 7 bit images. But on the other hand, the MSL images don't seem to loose detail in the whites the way MER images do.
I don't know if the MSL images have had any nonlinear pixel value transformations done, such as a logarithmic lookup table. I am curious what the images would look like with pixel value linearly related to the true scene intensity, and with the zero point correct. |
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