Help enhancing this image?

[Drahken]

http://allspark.net/cypherswipe/noisystripes.jpg
Any suggestions on how I could get a decent looking image out of that?
I often wind up with pictures like that as a result of trying to take digital pics under low light conditions (most often outdoors at night). The images appear black at first, but you find that there's a lot of captured detail if you crank up the gamma. The problem is that when you do that, you wind up with all that noise, and those stripes. A median cross filter seems to work best for getting rid of some of the noise (although no more than about 40%) without degrading the image in the process, but I can't find anything that works on the stripes.


(Yes, I've tried all the flash settings on the camera. In most of these cases though, the flash simply can't provide enough light for the large area involved.)

[helmut]

What you call "noise" are so-called hot pixels. If there's not enough light available, the sensor signal of the image censor is amplified and the noise, i.e. the wrong signals of the pixels on the censor is ampliefied, too. This generates the hot pixels.

When googling for "hot pixels" you will find many links including tools to eleminate / reduce hot pixels. (I'm a bit slack at the moment, so no links provided by me)

Greetings, Helmut

[Drahken]

Any idea what I kind do about those moire-like stripes?

[XnTriq]

Hi Drahken!

• PC World Australia: Imaging: Turn that noise down!
• Photo.net: Using Image Calibration to Reduce Noise in Digital Images
• Cambridge in Colour:
  • Understanding Image Noise
    • Part 1: Concept and Types
    • Part 2: Examples and Characteristics
  • Averaging Images to Reduce Noise
• GIMPguru.org: Reducing CCD Noise with The GIMP
  Digital cameras are prone to sensor noise, the digital counterpart to traditional film's grain. Learn how to ameliorate the problem of sensor noise.
• Jasc/Corel:
  • Digital Camera Noise Removal Filter (PDF, 2.5 MB)
    The purpose of this document is to explain how to use the Digital Camera Noise Removal filter to the best effect. In addition to explaining the various controls of the filter, the document provides an introduction to the nature of image noise and describes what to do with troublesome images.
  • Remove Digital Camera Noise
    Now you can get rid of those grainy specks that might mar your otherwise perfect photos. With the Digital Camera Noise Removal Filter, you can smooth your photos while maintaining the photo's texture. Follow along with this tutorial and we'll show you how to use this amazing Paint Shop Pro tool.
• MediaChance: BlackFrame NR — Noise reduction using Black frame method (Freeware)
  Perfectly remove Hot Pixels with different subtraction method:
  You need to take a “Black Frame”, a dark image with a lens cap on. Then use it with this amazing applet on your night shots.
• ABSoft: Neat Image — best noise reduction for digital cameras and scanners (Shareware, $29.90 - $74.90)
  Neat Image is a filter designed to reduce visible noise and grain in photographic images produced by digital cameras and scanners. Neat Image is indispensable in low-light (indoors, night, astro) and high-speed (sport, action) photography. It is a tool for both professional photographers and digital image processing enthusiasts.
  • Filtration examples — what is possible with Neat Image
    Below are several examples of digital images with visible noise of different nature. Generally, noise can be brought in by the camera sensor and signal amplifier, by peculiarity of shooting conditions, by image compression, etc. In many cases, Neat Image can significantly improve the quality of the digital images by reducing the objectionable noise. Please compare some before and after images below to see what Neat Image can do.
• PictureCode: Noise Ninja — The gold standard for image noise reduction (Shareware, $34.95 - $79.95)
  Noise Ninja is the most effective and productive solution for removing noise and grain from digital photographs and scanned film images. It is a must-have tool for anyone shooting in low-light or fast-action situations — including news, sports, wedding, and event coverage — where high ISO photography is required and the resulting noise compromises the image.
  Noise Ninja often yields a two-stop improvement in effective image quality, while preserving important image detail. In addition, it can produce cleaner, smoother enlargements from low-ISO images.
  • Noise Ninja in action: Before-and-after examples