Fortunately, you can get sharpen the image to partially offset this. Here is the original image. Notice how bad the noise is, especially in the shadows of the face and in the white wall back right.
Try it if you have an especially noisy image. Examine the resulting image, zooming in to examine shadow areas. Unfortunately, you may also notice that the image is softer; the despeckle filter actually blurs the image. Fortunately we can offset this to some degree by sharpening. You can search them in theyr groups, but the fastest way to find them is to use the search bar.
Let's see in detail their functionality and the differences that distinguish them in noise reduction. For those who want to make a more in-depth testing, next you can download our test files, that are available in full resolution. Remember that you should always use your photos to perform a tests, because ours have been compressed. For each filter there will be three images: the first is the ideal photograph, taken at ISO. The second is the photo at 3,ISO with the corresponding noise reduction applied.
The third is the photo at 12,ISO with the reduction applied. Since the crop is rather small, there will also be links to download the images in high resolution, obviously with noise reduction applied. It's not easy to compare them because of the distance, so after the explanations we'll put them next to each other for a better comparison.
With the standard parameters you can already get some excellent results, but increasing the Amplitude to and reducing the Anisotropy to 0. On the 12,ISO photograph it was necessary to raise the value of Amplitude to If you mess up the various parameters while trying different settings, you can go back to the initial conditions by clicking on the upper right arrow.
If you want you can see the photos in original resolution with the Smooth [Anisotropic] filter applied with the default parameters : here you find the file at 3, ISO and here the file at 12, ISO.
To counter this issue we had to lower the Sharpness , but the lost of detail could be too much. It is necessary to balance, according to your personal taste, two parameters: Amplitude , which we have raised to , and Sharpness , which we have lowered to 0. The results are not bad at all, keep a lower sharpness helps to hide the "brushstroke" effect.
This tool for digital noise reduction with G'MIC is really good. If you prefer to see the photos in original resolution, with the Smooth [Thin brush] filter applied with the default parameters here you find the file at 3, ISO and here the file at 12, ISO. It reduces the image sharpness more than the other two, but is particularly effective for photos with a lot of noise.
We recommend to set the value Amplitude to and change the Sharpness according to the noise. We used 0. If you want to see the result in high resolution with the filter at the default parameters you can download here the file to 3, ISO and here the file at 12, ISO.
For an easier comparison below you can see, side by side, the three filters with the recommended settings. I'm sure that you can do this in GIMP without plugins, a quick googling results that maybe helpful:. You could use try some of the filters from G'mic a "plugin pack" for the Gimp which has a lot more filters than just noise removal ones.
Here's its website and download page. For a tutorial: Noise reduction with G'Mic. An excerpt:. Anisotropic Smoothing is the best solution for pure noise reduction, it can be found under Enhancement and will give you the lower loss of details, and last but not least is really easy to setup. Usually, the blue channel has more noise than the others. So an old trick is applying a slight blur to the blue channel might help. That said, noise reduction software like Noiseware and Noise Ninja are so far advanced beyond this old trick that you might find it worth your time and money to look into a more automated solution.
You can always scale down your picture to reduce noise. The scaling operation will average groups of noisy pixels, this cancels some of the noise out. You can do this alone or after you apply other noise reduction techniques.
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