Sometimes the PNG image you get from Slooh.com has a grainy appearance, like the following image:

The graininess is noise and can be caused by a number of different things, including the processing preset that you chose or was selected for you when you booked the mission.

In this article, I walk you through the steps to reduce the noise in the image by using a Gaussian Blur, but only on the image’s background, leaving the subject of your image unchanged.

This is the resulting image after following the steps in this article:

The noise is less apparent and the comet is still intact. The stars have become less apparent because I used aggressive settings for this article to make the changes more apparent.

Reducing Noise Using a Gaussian Blur

  1. Point your browser to Photopea.com

2. From the menu, select File – Open and open the image you’d like to modify. You can use the image at the beginning of this article, just save it to your system and open it in this step.

3. In the bottom right, where it says Layers | Channels, right-click the Background layer and select Duplicate Layer from the menu that pops-up

4. From the menu select Select-All, followed by Edit – Copy

5. From the menu, select Layer – Raster Mask – Add (Reveal All)

6. Press and hold the ALT key on your keyboard and click the white box beside Layer 1 at the lower-right. This turns your screen white and is expected.

7. From the menu, select Edit – Paste to paste your image into the mask

The mask is reversed at the moment – it is protecting the background but we want to affect the background, so we’ll have to invert the image and modify it to protect the comet and stars

8. From the menu, select Image – Adjustments – Invert

9. From the menu, select Image – Adjustments – Levels

10. Adjust your image to bring out the comet or your subject. In this case, I adjusted the mid tones and highlights sliders as shown:

The mask image is very noisy and to produce a better end result, we’ll add a little blurring to the overall mask.

11. From the menu, select Filter – Blur – Gaussian Blur and adjust the image so that it has less noise, as shown:

Your mask is ready now

12. Click the dark image next to Layer 1, as shown:

The comet/your subject appears again

We can now apply a Gaussian Blur to the background pixels as follows:

13. From the menu, select Filter – Blur – Gaussian Blur

14. Adjust the Radius slider until you see a satisfactory result, noting that only the background is being affected. In my case, I selected a radius of 4.5 px, as shown:

15. From the menu, select Layers – Flatten Image

16. Save or export your resulting image using the File menu

Conclusion

In this article, you learned how to reduce noise in a Slooh.com PNG image using an inverted mask.