Using The GIMP (or Photoshop) to Improve Photos? 111
Nom du Keyboard asks: "Is it possible to use The GIMP (or Photoshop) to improve my digital photos? I have a mid-range 7.1MP Olympus camera capable of shooting in Raw mode. When I inspected a section of clear blue sky on a bright, sunny day (which I've long believed to be relatively good reference of uniform color and brightness) I was surprised (disappointed, since I expect digital perfection) at the variance in adjacent pixels. It's also a quick way to identify any bad pixels. Surprisingly, actual photos from this camera look pretty good despite this variance so far. Moving on from that point it led me to wonder that, if you shot a uniform white surface, perhaps blurred as much as possible to avoid any imperfections in the surface itself, could a correction (adjustment) layer be created in GIMP or Photoshop exactly tuned to your camera that fixed the variations in your CCD sensor and improved the image quality in the process. Any thoughts?"
Yes. (Score:4, Interesting)
Or GREYCstoration (Score:5, Interesting)
Re:Yes Exactly! Only Backwards.... (Score:4, Interesting)
I doubt that that will work. Once in the computer, the pixel values are not proportional to the absolute brightness, see gamma correction [wikipedia.org] on wikipedia. You would need to do the substraction on linearly encoded data (12 or more bits rather than 8). Maybe photoshop can indeed do this, provided you find the right settings, but GIMP as far as I know doesn't.
Re:Something similar (Score:3, Interesting)
Re:try it (Score:1, Interesting)
I think that this section has had 1 good question in the last month.
Re:Something similar (Score:3, Interesting)
Dark frames aren't actually as useful anymore for instruments on larger telescopes that use LN2 or a cryotiger for cooling.
Re:Yes Exactly! Only Backwards.... (Score:3, Interesting)
Photoshop has:
Adjustment layers which allow you to change filters after the fact
Filter layers which allow you to switch a stack of filter on and off and season to taste after tha fact (in CS3)
These two features allow you to view image processing more like a spreadsheet in the same way that Excel is better than a calculator
Can do filters on the GPU in hardware (in CS3)
Save for web
Absolute color systems (Lab color)
Capability too do color proofing for printing presses (needs absolute color conversions)
Import and manipulation of smart object layers and changing them after the feact
Layer styles which allow you to change the llayerr after the fact. With copy and paste which are really useful to make lots imagges in the same style
16 and 32 bit and HDR color
Better macro recording (Gimp is probably easier too program though)
The history brush
The patch tool
MUCH better image size interpolations (if you resize an image iit look better in PS
A text tool that dooes preview on the image and not in some box outside of it
Much better text layers
A UI that was not written by the spawn of Satan
Basically, Photoshop is like a spreadsheet and GIMP is like a calculator. PS allows you to do do much better look and feel stuff
An no, the price comparison argument does not really hold. Gimp's competitor is Photoshop Elements which has all the features except the press stuff.
Re:"as bright as possible" is useless (Score:3, Interesting)
Replying to TFA:
Digital perfection does not exist! You (the submitter) are taking images of the real world, where light moves around somewhat randomly in energy packets called photons, not in perfect rays. Noise can not be eliminated, ever. There's also some noise from the electronic components of the camera itself, which you also have to live with, unless you get a better quality camera. Or use some careful noise reduction. You do have the option of creating digital perfection, though. 3ds Max is popular, I gather.If color variance is the problem, however, that's due to the CCD design. The CCD in nearly every camera is a single chip for all three colors (4 in some rare cases), but a single photosite ("pixel") can only detect one color. This means the sites need to be mosaiced in a regular pattern, usually RGBG, which is then decoded into a raster image like JPEG. For your 7.1 Mpix camera, than means about 3.5 Mpix resolution for green golors, and 1.8 Mpix for red and blue each. This can cause colored blotches in supposedly even areas, but this kind of noise is fortunately really easy to remove with any decent noise-removal plugin. Perhaps it's possible to avoid this noise in the conversion from the raw data, though?
Most importantly, inspecting the noise of a camera by oogling at 200% isn't very useful, look at larger areas instead. Most noise disappears when put into its normal scale for viewing.
To answer the last question in TFS, yes, if there are bad pixels, it's not hard to find them and create a mask or an action (in PS) that eliminates them. You can also take a noise print for your camera at different ISOs/shutter speeds (at least in Neat Image), and store them for later use in other photos, so you don't need to analyze the noise over and over again. Again, if you want less noise to begin with, make sure you're using the lowest ISO setting that gives you a usable shutter speed, or get a camera with larger sensor area, that can capture more photons in the same amount of time. Also remember that some noise is good noise. A noiseless picture tends to look a bit unnatural, so don't try to remove all of it.