To make photos less blurry in Krita, follow the following steps:
1: open the image you want to edit in Krita.
2: on the "Layers" panel, there's a "plus" button that adds a new paint layer. On its right side, there's a small arrow which, when clicked, opens a popup menu where you can select other types of layers to add. Click on the arrow and select the option "Add Filter Layer...." A dialog box will appear.
3: the dialog has a list-detail layout: on the list pane, select "Enhance -> Unsharp Mask." The detail pane will change to display the settings to configure this filter.
4: the unsharp mask filter has four settings:
- Radius: how large is the blur of the image.
- Amount: how strong is the anti-blurring effect.
- Threshold: avoids creating noise on flat areas.
- Lightness Only. applies the effect only to lightness as a whole, as opposed to each color channel separately. Keep this checked.
In most cases, photos are only slightly blurry, and a radius of 1 or 2 pixels will be enough. You can of course increase this, but increasing it can lead to an "outline" effect appearing.
The way unsharp mask works is that it tries to figure out where are the edges of the image, and then it inverts the colors (or, in our case, the lightness) of those edges. The size of the area inverted is the "Radius," and the strength of the inversion is the "Amount."
With smaller radii, this inversion creates a subtle outline that increases the contrast, making the image appear sharper. With larger radii the outline becomes obvious, which has a detrimental effect on the quality of the photo because then everyone will know you used weird filters on it.
Increasing the amount or strength of the unsharp mask will make details on the image much more clear than normal. Things like textures on clothes, pores, etc. will begin standing out due to the increased contrast. If this amount is too high, the image will appear "textured" like some sort of paper. Essentially, the photo has some noise in it that is normally imperceptible, just like pores on the skin, but becomes far more perceptible if you keep adding contrast to it. One way to avoid it is to use the "Threshold" setting to stop the filter from adding contrast to edges with values under that threshold, but this setting isn't perfect either, so, realistically, the only option is to use less strength. The image won't look as sharp you want, but at least it won't look full of noise either.
Adjust the radius and amount until you get a result that looks good enough for you.
The unsharp mask is a trick that can make the average photo taken from a poor-quality smartphone camera look much better than normal. It will only look a bit sharper than before, as we want to avoid noise that comes with greater strengths, but even this subtle sharpness should be enough to make your photos look much higher quality than they originally were.
5: after you finish configuring the filter layer, click OK to finish creating it. The newly created filter layer should appear in the "Layers" panel.
Note: you can modify the settings of the filter after you created it by right clicking on it in the "Layers" panel to open its context menu and clicking on "Properties..." (keyboard shortcut: F3).
6: click File -> Export in the menubar to save your finished photo.
Video
Observations
The unsharp mask is a very common filter found in several applications. This same tutorial also works on GIMP, Photoshop, Affinity Photo, etc.
If you're just using unsharp mask, it's easier to do it in GIMP than in Krita. In Krita, the filter settings dialog is modal, meaning that you can't click on the panel to show/hide the filter while you're editing its settings. There also isn't a button to switch the preview on/off, which means you need to click OK to close the dialog in order to compare how much blur you removed from the image. In GIMP, all of this is possible. On the other hand, GIMP's stable version still doesn't have non-destructive filter layers, and you'll probably want to make other edits to your photos, like changing brightness, in which case Krita will be more convenient.
I've read that the threshold setting is supposed to get rid of noise, which should make the image look better, but when I tried it I found it doesn't really produce good results. It reduces the amount of noise overall, but when the entire image was noisy, that felt like a feature of the camera, whereas when only part of the image is noisy, that looks like someone deliberately added noise to the photo or forgot to remove it.
Acknowledgements
Photo used in this tutorial by: Gilbert-Noël Sfeir Mont-Liban, via Flickr. License: CC BY 2.0.
Leave a Reply