photo.net— Images taken from digital cameras tend to have a lot of noise which makes the image look amateurish. Here are some tips on how you can get rid of the noise.
Oct 27, 2005View in Crawl 4
That was a bad camera to use for the example. That article doesn't really apply to "regular" digital cameras. You aren't going to be taking 30 or 60 minute exposures with a regular digital. You also aren't going to be taking pictures at iso3200,1600, and probably not even 800 with a normal camera. Several of the prosumer digital SLR cameras have a noise reduction feature built in for long exposures. When you enable the feature and take a long exposure shot the camera will immediately take another exposure after yours finished. It will be the exact amount of time as the first exposure but will be with the shutter closed. It'll then use that second image to cancel out the noise in the first image. Basically, the kinds of noise he is talking about don't really apply to non-prosumer or above cameras that can't take extended exposures at lowlight iso settings.
Neat Image (<a class="user" href="http://www.neatimage.com/index.html)">http://www.neatimage.com/index.html)</a> is a tool that removes noise from photos or scanned images. For best results, you print a calibration image and scan or photograph it. Neat Image analyzes the noise profile and creates a filter for those specific conditions. Submit your profiles to share on their web site and get a free home version registration code.Regarding consumer cameras that save as JPEGs... That's why I still use a 35mm film camera and a good scanner to save images as uncompressed TIFF. I can't afford a digital camera that would provide better results.
@soulcages01, first take the regular picture with the settings set to RAW and no sharpening. Then put on the lens protector, cover the lens in something like a towel (to make it totally dark), and snap one more with the same settings.Open up both images in Photoshop and paste the black one in a layer on top of the regular picture and set the blending mode top "Difference".There. Kind of.
If you're shooting jpeg, you have to be really careful because any processing that you do can easily degrade the image. Jpeg is the mp3 of the photo world. It is 8 bits/channel compressed, whereas your cameras sensor is probably capturing at 12 bits/channel uncompressed. Programs like Noise Ninja or Neat Image can help, but are best used sparingly. They work best on files that have been properly exposed initially, shot in raw and converted to an uncompressed format such as tiff. Other than that, it can be touch and go.The best practical advice to getting noise free images from digital point and shooters is to get a good exposure at capture.Most consumer cameras are set to underexpose by as much as a 1/2 stop or more to prevent 'blowing out' the highlights in a given scene. It may seem prudent to leave this 'headroom' at capture because pictures can be easily brightened, or lightened during image processing on the computer. The problem with this method is that a disproportionate amount of data is allotted for the brighter parts of a scene when the camera renders an image. If you take a picture, and the histogram shows no data above the midpoint of the plot, you've not thrown away 6 of the possible 12 bits at capture - you've thrown away more like 8. The resulting image looks 'noisy', but really, the noise (as discussed in the article) isn't the reason for the poor image quality - the reason is the quantization of tonal levels. The ideal digital exposure should have a histogram plot that is justified to the right as much as possible without data clipping. It is way better to have to darken your images during processing than lighten them.Most point-and-shooters will still have exposure compensation - even if it is hidden under sub-menus. Setting this to somewhere between +1/3 to +1 can help your image quality much more than heavy handed processing.
mathew_bugOct 28, 2005
kawai: try Noise Ninja ;) > <a class="user" href="http://www.picturecode.com/">http://www.picturecode.com/</a>
dodger2020Oct 28, 2005
That was a bad camera to use for the example. That article doesn't really apply to "regular" digital cameras. You aren't going to be taking 30 or 60 minute exposures with a regular digital. You also aren't going to be taking pictures at iso3200,1600, and probably not even 800 with a normal camera. Several of the prosumer digital SLR cameras have a noise reduction feature built in for long exposures. When you enable the feature and take a long exposure shot the camera will immediately take another exposure after yours finished. It will be the exact amount of time as the first exposure but will be with the shutter closed. It'll then use that second image to cancel out the noise in the first image. Basically, the kinds of noise he is talking about don't really apply to non-prosumer or above cameras that can't take extended exposures at lowlight iso settings.
justmy2__Oct 28, 2005
Neat Image (<a class="user" href="http://www.neatimage.com/index.html)">http://www.neatimage.com/index.html)</a> is a tool that removes noise from photos or scanned images. For best results, you print a calibration image and scan or photograph it. Neat Image analyzes the noise profile and creates a filter for those specific conditions. Submit your profiles to share on their web site and get a free home version registration code.Regarding consumer cameras that save as JPEGs... That's why I still use a 35mm film camera and a good scanner to save images as uncompressed TIFF. I can't afford a digital camera that would provide better results.
rauzOct 28, 2005
@soulcages01, first take the regular picture with the settings set to RAW and no sharpening. Then put on the lens protector, cover the lens in something like a towel (to make it totally dark), and snap one more with the same settings.Open up both images in Photoshop and paste the black one in a layer on top of the regular picture and set the blending mode top "Difference".There. Kind of.
loginidOct 28, 2005
If you're shooting jpeg, you have to be really careful because any processing that you do can easily degrade the image. Jpeg is the mp3 of the photo world. It is 8 bits/channel compressed, whereas your cameras sensor is probably capturing at 12 bits/channel uncompressed. Programs like Noise Ninja or Neat Image can help, but are best used sparingly. They work best on files that have been properly exposed initially, shot in raw and converted to an uncompressed format such as tiff. Other than that, it can be touch and go.The best practical advice to getting noise free images from digital point and shooters is to get a good exposure at capture.Most consumer cameras are set to underexpose by as much as a 1/2 stop or more to prevent 'blowing out' the highlights in a given scene. It may seem prudent to leave this 'headroom' at capture because pictures can be easily brightened, or lightened during image processing on the computer. The problem with this method is that a disproportionate amount of data is allotted for the brighter parts of a scene when the camera renders an image. If you take a picture, and the histogram shows no data above the midpoint of the plot, you've not thrown away 6 of the possible 12 bits at capture - you've thrown away more like 8. The resulting image looks 'noisy', but really, the noise (as discussed in the article) isn't the reason for the poor image quality - the reason is the quantization of tonal levels. The ideal digital exposure should have a histogram plot that is justified to the right as much as possible without data clipping. It is way better to have to darken your images during processing than lighten them.Most point-and-shooters will still have exposure compensation - even if it is hidden under sub-menus. Setting this to somewhere between +1/3 to +1 can help your image quality much more than heavy handed processing.
truebloodOct 28, 2005
I second the suggestion to use Noise Ninja. Great program.
thegooseyoneOct 28, 2005
oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooold