I've been trying for the last day or so to find a way of processing mars that doesn't exaggerate the "hard edge" that we all seem to get, and I've made some progress.
Have a look at the attached image, again it's one from sept 24 but I don't have any new ones to try - it's been raining the last couple of days :-(
The edge is now a thin blue line, I think that's probably close to correct since there is an atmosphere and dust etc, we should see something around the sunlit side.
Now something else has shown up that's very interesting - look near the south pole and you'll see that the haze there is green, not blue. I hadn't seen this before, I think the true colour was lost in the overbright edge.
Overall I think the colour is better - Olympus Mons is now distinctly visible and it's a different shade of red to the surrounding plain.
Here's what I did, please try it and see if it helps your images:
- In registax wavelets, be gentle. You don't have to do all the sharpening in that one step, we can apply unsharp masks etc later on. Set layers 5 and 6 to -1 or maybe even less, this should help reduce the edge by subtracting off large, bright bits of the image.
- Next, save the image and load it into your favourite photoshop-like program. I use Astra Image, but I guess photoshop or similar would do as well.
- If you have a high-pass filter, try applying that. It will increase the contrast in the image without enhancing the edge.
- Apply an unsharp mask with a reasonably large radius, but only gently.
- Now smooth the image with something like an "alpha-trimmed mean" or "3x3 gaussian mean", whatever you've got. There will be artifacts introduced by the previous sharpening stages to get rid of, and this smoothing will help do that.
- Now apply another unsharp mask with a smaller radius to highlight the remaining features.
This is what works for me, but please remember that your mileage will vary, depending on your raw data.
I'd love to hear if this sort of approach can give you good images without exaggerating the hard edge.
regards, Anthony
Have a look at the attached image, again it's one from sept 24 but I don't have any new ones to try - it's been raining the last couple of days :-(
The edge is now a thin blue line, I think that's probably close to correct since there is an atmosphere and dust etc, we should see something around the sunlit side.
Now something else has shown up that's very interesting - look near the south pole and you'll see that the haze there is green, not blue. I hadn't seen this before, I think the true colour was lost in the overbright edge.
Overall I think the colour is better - Olympus Mons is now distinctly visible and it's a different shade of red to the surrounding plain.
Here's what I did, please try it and see if it helps your images:
- In registax wavelets, be gentle. You don't have to do all the sharpening in that one step, we can apply unsharp masks etc later on. Set layers 5 and 6 to -1 or maybe even less, this should help reduce the edge by subtracting off large, bright bits of the image.
- Next, save the image and load it into your favourite photoshop-like program. I use Astra Image, but I guess photoshop or similar would do as well.
- If you have a high-pass filter, try applying that. It will increase the contrast in the image without enhancing the edge.
- Apply an unsharp mask with a reasonably large radius, but only gently.
- Now smooth the image with something like an "alpha-trimmed mean" or "3x3 gaussian mean", whatever you've got. There will be artifacts introduced by the previous sharpening stages to get rid of, and this smoothing will help do that.
- Now apply another unsharp mask with a smaller radius to highlight the remaining features.
This is what works for me, but please remember that your mileage will vary, depending on your raw data.
I'd love to hear if this sort of approach can give you good images without exaggerating the hard edge.
regards, Anthony
Attached Image:
http://www.acquerra.com.au/astro
