Author: Mike Boesen

Last updated: 3 July 2007

1.  Background

In June 2007 I wrote a small article about camera review sites that are very useful in getting information about digital cameras prior to selecting one to buy:

In that article I referred to an application named Neat Image which I use to reduce noise in digital images that I have taken in low light situations. 

In this small article I have provided some more information about Neat Image.

I am not a skilled photographer.  My views are based on use of three digital cameras:  Sony DSC F717, Canon Powershot A700, and Canon Powershot A710 IS. 

2.  Need for a de-noising application

While I use my cameras' in-built flash on occasions for fill  lighting, the results I usually get in normal in low light situations are not satisfactory.  I often end up with pictures that are reminiscent of 'startled deer in front of the headlights'.  Other problems are shadows created by the flash and reflections of the flash from glass surfaces.    On occasions I have used a more powerful external flash with better results, but that requires preparation and the additional equipment.  Most of my pictures are taken in situations where I would not be prepared to carry around an external flash and go through the business of setting it up.  So most times I do not use flash at all, but rely on using my cameras high ISO setting.  In many low light situations, taking pictures using high ISO settings can result in very pleasing or at least adequate results.   I won't attempt to explain what a high ISO is - there is a multitude of stuff on the web that explains much better than I can.   Here for instance is a good, short readable article:

If your digital camera supports high ISO settings and you use such a setting through the automatic mode or under manual control, some pictures will display 'noise'.  Usually, this evidences itself as red and/or purple and/or green blotchiness over the whole image.  It is most visible on uniformly coloured surfaces such as walls and is particularly visible when you magnify an image.  It becomes a particular problem when you want to crop a picture prior to printing it and/or print something larger than a postcard size.

The amount of noise varies from camera to camera, the ISO level used, and the particular type of CCD (Charge Coupled Device) image sensor that the camera uses.  Some brands of cameras appear to generate more noise than others.

3.  Noise-reduction applications

There are a number of applications that can be used to reduce the amount of noise in an image.  An excellent review of applications is here:

As you will note from the review there are considerable differences between applications in terms of the quality of the output. 

Some applications run as stand-alone applications and some function as plugins for editing applications like Paintshop Pro or Photoshop Pro.

I have been using one of the better-rated applications - Neat Image Pro (version 5.2) - for some time and its ability to improve some of my high-ISO low-light shots is magical.  It can be installed as both a stand-alone application and as a plugin for Paintshop Pro, Photoshop Pro and MS Digital Image Suite.  In addition to the payware Pro version, there is a free non-time-limited 'Demo' version.  Both are available here:

Both the Pro and Demo versions have identical functionality in terms of comprehensive options for removing noise and sharpening.   However, unlike the Pro version, the Demo version will save de-noised output only in JPG format and the JPG compression level cannot be controlled.  The Pro version will save in JPG format with user-determined compression levels, or as TIF or BMP format. 

While the Pro version can be used as a stand-alone application or as a plugin, the Demo version only functions as a stand-alone application. 

While it has lesser functionality, the free Demo version is well worth trying and will probably meet the needs of most amateurs. 

Neat Image has extensive functionality for variation to settings.  You can create your own settings or use any of a number of presets.  The presets are accessed through the Noise filter settings tab - go to Filter Presets / Filter and sharpen image / Advanced.  The preset that meets many of my needs is 'Filter and slightly sharpen out of focus image'.   You need to experiment with the various presets to see which best meets your needs.  After than you can also create your own presets and save them for future use.

I have posted some sample test pics in a PicasaWeb album here:

In the first set of three images, I started with a test shot of myself taken in a dark room with no lighting, shot at ISO 800 and without flash.  I then cropped the original image and lightened it up using Picasa2.  The noise engendered by the high ISO plus the zoom-like result achieved by cropping is very obvious in that second image. The third image is the second image after de-noising and sharpening using Neat Image.  As you can see, the image is much improved (although it did nothing to make me look younger).

The fourth image is a crop of a picture taken without flash at 800 ISO under atrocious lighting conditions.  The fifth image is that picture de-noised and sharpened using Neat Image.

4.  Limitations

If you need to sharpen an image, that can be done in Neat Image at the same time as you reduce noise. Noise-reduction and sharpening will lead to some loss in detail and creation of artifacts.   How much loss or artifact creation occurs is a function of the particular settings that you implement and how aggressive they are. 

With the exception of cropping, I prefer to undertake processing in Neat Image prior to any other editing.  My theory is that the noise reduction process should be undertaken on an image that has not lost any information - such as would be the case if it were edited in some other application then saved as a transformed image.  So after cropping outside Neat Image, I then reduce noise and undertake sharpening within Neat Image, save the image with nil compression (as a TIF file) or as a JPG file with minimal compression, then do any other editing within Photoshop.  Of particular importance is to NOT undertake image transformation such as sharpening prior to processing within Neat Image.

5.  Conclusion

Digital images that have a lot of noise - such as those created using a high ISO or with a less effective CCD image sensor - can be improved considerably using de-noising applications.  The application that I use for this is Neat Image.  I have used it with great effectiveness on many digital images.  I'd recommend that you try at least the free Demo version of Neat Image.

I have also tried Noise Ninja and it is another good application.  However, I think that it does not have a freeware version.


Mike Boesen