Adding a controlled soft focus to a photo
I'm assuming you've got Inkscape running.
I'm also assuming you've got some basic knowledge of how to use Inkscape.
import an image
From the toolbar:
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From keyboard: Ctrl + I
From the menus: File → Import...
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Snap the image into place
From the menus: Extensions → Modify Path → Pixel Snap...
While this step is optional, it is recommended to align the pixels of your image with Inkscape's invisible grid to prevent the image from being exported in a fuzzy way. Now, I know this is a tutorial on making the image... fuzzy. But what we're looking for is a fuzziness that we control and not one imposed on us by the software.

--Thanks 'prkos' for that tip.
copy the image
From keyboard: Ctrl + C
From the menus: Edit → Copy
open layers dialogue
From the toolbar:
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From keyboard: Ctrl + Shift + L
From the menus: Layers → Layer...
- Resize the dialogue box enough to see all its options.
create a new layer
From the menus: Layer → Add Layer...
From the Layers dialogue: click the + icon
- Give the new layer the name "SoftFocusEffect" for this tutorial.
- Click the Add button.
- Once the layer is created, do not close the Layers dialogue.
paste the copied image in place
From keyboard: Ctrl + Alt + V
From the menus: Edit → Paste In Place
- You won't see a difference at this point
- The copied image sits directly on top of original
open the Fill and Stroke dialogue box
From the toolbar:
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From keyboard: Ctrl + Shift + F
From menus: Object → Fill and Stroke...
move the blur and opacity sliders till satisfied
- The sliders are in the Fill and Stroke dialogue box.
- Start by reducing Opacity to 50.0.
- Follow by raising Blur to 5.0.
- Continue to adjust sliders till you have the best look.
lock the SoftFocusEffect layer
- In the Layers dialogue box click the small lock icon left of "SoftFocusEffect"
- Click the image again.
export your image with soft focus
From the toolbar:
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From keyboard: Ctrl + Shift + E
From menus: File → Export Bitmap...
- Export Area: leave it at "Selection"
- Bitmap Size: 300dpi for printing, 96dpi or 72dpi for webpages
- Filename: Use the Browse button choose where to save the file.
Note: if there's any improvement on this short tutorial that you can recommend, do not hesitate to suggest it.