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Noise Ninja - Removing Image noise

A photoshop plugin that works wonders on your images

The Canon 1Ds that Keith regularly uses, has very little noise in images produced at the ISO 100 setting, however at higher speeds noise can become objectionable. Just as with film it's the price you pay for increased sensitivity. Noise Ninja (link to picturecode site) has been round a while as a standalone application, but is soon to be released as a Photoshop plugin. As a plugin it potentially becomes a much more usable part of Keith's imaging workflow. Keith has been reviewing some of its features and finding just how well it works. Do bear in mind that as of writing this review, the plugin is still Beta software, and may well still have some glitches. If you do try the demo, just remember to back up those important images! The software was tested on a Mac running OS X 10.3.7 and Photoshop CS. Noise Ninja also works on PCs.

Why do you get noise in images?

Any system for capturing images will also produce some unwanted image content, in the form of noise. The film equivalent is grain and on TV it can appear as 'Snow'. Noise is everywhere, it is a fundamental feature of sensor design, whether for a digital SLR, a small 'compact' digital camera, or a film scanner. In general, the more sensitive, or smaller, you try and make a sensor, the more noise it will show. Different devices also exhibit different patterns of noise, varying with lighting and colour. One of the results of this is that there is no simple way of removing noise, it always depends on the device, how it was used and any processing of the image data.

If you'd like some more detailed info on sensor noise...

Understanding Noise (on the PictureCode site)
Noise in digital sensors - part of a very useful collection of info at ExtremeTech

So, it's there whether you like it or not. What can you do about it?

What does the software do?

If you take a picture of a known scene (a test chart for example) you can compare what you see with what there should be. This difference can be used as a 'profile' in order to correct the captured image. Sounds simple, but there is an awful lot of complex maths that goes into making a 'Noise profile' and then using it to correct a real picture.

Noise Ninja offers you three ways of getting the profile you need.

1. Download a profile for your camera from PictureCode
2. Photograph a test chart and create your own profile
3. Get Noise Ninja to try and construct a profile based on the image you are correcting

The software comes with a test image you can print out and use as a chart. The precision and colour accuracy required is not at all like profiling a printer, so I just printed out an A4 copy on good quality photo paper on an Epson 1290. Since the software is looking for noise generated by your camera, you get the best results if the image is slightly out of focus. This may take a bit of experimenting if you are using an autofocus camera. You could try very close up or even take the picture whilst jumping up and down :-) The image should be correctly exposed so as to get a full range of colours and range of brightness.

A much reduced version of the test chart included with the software.

The software will analyse the picture and select parts of it to use in building up a profile. You can also select the areas to analyse yourself. The software offers numerous areas where you can fiddle with settings and setups, if you are so inclined. More importantly to me, most of the default settings were fine, the only change from defaults for this review was to turn off image sharpening, since I like to know when and where in my workflow that sharpening is being applied.

	The main plugin window, showing a magnified section of the whole image. A profile for this image has been loaded. The results of the filter are shown in real time in the magnified section.
	A profile has been loaded. The naming convention is such as to facilitate automatic profile loading in the final version of the plugin. In this instance I've loaded the ISO 100 version for the Canon 1Ds
	Lots of adjustments for you to fine tune the filter. I've switched off USM (sharpening) here

The software works fine on 8 or 16 bit images. It works on RGB and greyscale images. Although not detailed here, I also tried it on some old film scans (35mm Canon FS4000) and the improvement was quite noticeable.

I'm pleased that a lot of thought has been given to the help files and general interface layout. It's easy to use and even has a '5 Minute' guide for the impatient

Does it work?

The first examples are from pictures of my piano that were taken with a Canon 1Ds and are from raw format files, converted using Adobe Camera Raw. The first picture has been edited a bit to give an impression of what the scene actually looks like.

The room picture, as converted, using Adobe camera raw on an ISO 1250 file from a Canon 1Ds

Move your pointer over the two images below to show the effects of the noise removal (and unfortunately some JPEG compression artefacts)

Both these images have been given no additional sharpening. Please do remember the difficulties of showing subtle image changes in web images (these are JPEGs) and try your own comparisons.

The kebab shop

This picture (left) was used in the DxO Raw Converter review (ISO 1250).

100% crop (ACR conversion) Move your pointer over the right image to show the results of applying Noise Ninja.

The Looking Glass

An ISO 1250 picture from the 'Looking Glass' bar, converted using DxO raw converter. This was processed with the Canon 1Ds 1250 ISO profile. The results were slightly better with a custom noise profile created from a DxO raw conversion, but not really enough to show up on the web.

A 100% crop is shown below.

Move your pointer over the image above to show the results of applying Noise Ninja.

Any old camera...

Several years ago I got an Olympus C1400XL -- actually my first digital SLR. I still use it for a bit of teaching work (all the images in the Photoshop Elements tutorials are from it)

One of the reasons I tried this camera was to see how well the profiling would work with an arbitrary choice of imaging device. The first picture shows a (reduced size) JPEG from the camera. The lighting conditions would be a challenge for more modern cameras :-)

The second version is after noise removal, colour balancing and application of the Photoshop Shadows and Highlights filter

The target print was photographed and a noise profile created.

The examples below (100%crops), show how the noise reduction shows up more after the image has been processed.

Moving your pointer over the images shows the Noise Ninja processed versions.

(1) Original image before and after noise reduction. Note how the noise reduction does not show up very much.	(2) Images from previous example after application of Photoshop 'shadows and highlights' tool. The noise in the darker parts of the image is now much more visible, and the effect of Noise Ninja is much more obvious.

This illustrates how much noise can lurk in shadows, just waiting for your next levels or curves adjustment to bring it out into the open...

The Photoshop CS Shadows and Highlights tool is great for quick fixes like above, but has the flexibility to do a lot more. I have several batch processing Photoshop actions that include it as part of my workflow.

Is there a downside?

The software tested is a beta version so it still lacks a few features found in the stand alone version.

With any software, when removing unwanted image features, there is a danger that you will lose image information (such as colours or detail). The examples above are unsharpened and use default settings, but for finest quality you may need to tune the filter settings. My suspicion is that (in the real world) very few images will require such adjustment :-)

Summary

A splendid bit of software that lets me use my 1Ds at high ISO settings without too much concern for noise. Of course I tend to use it at ISO 100 for my landscape work, but I do quite a bit of event photography without a flash, where noise is a real issue.

You can employ Noise Ninja at any time in your workflow. It should be noted however that the profiles are relevant to a particular combination of image sensor, capture settings -and- processing options. If you are looking to optimal results then you should make up your own set of profiles for a camera. For example, I might have Canon 1Ds ISO 1250 profiles for Adobe camera raw conversion, as well as the DxO raw converter I use for some work. If you want to be really precise you might want profiles at differing white balance settings. Of course if you are lucky, someone else will have done the work for you (you can contribute profiles at the PictureCode web site)

There are several areas of the software that are not yet available in the plugin, one important area is the automation of profile selection (annotations) which allow you to base profile selection on various image parameters (from EXIF data for example). This would be particularly useful for incorporation into a batch conversion process where you might have one or two high ISO shots mixed in with others at lower speeds.

I'd happily suggest you give Noise Ninja a try. You can get a demo (the plugin or stand alone version) at http://www.picturecode.com/download.htm

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