Depth-of-Field Editing Post Capture: Isolating and Blurring a Flower’s Background in Photoshop

Flowers, Irises, Photoshop, Software, Tips

1/320 f/5.6 ISO 100

The background of this image isn’t terrible, but it’s not great, either. After a recent post-capture edit of a background to isolate the subject and make a pure, one-color or block color background, I decided to try the other most popular look, i.e., blurring. This is typically done to make it appear as if the photographer used a high depth of field (DOF).

It’s a common problem in garden photography to have a ‘junk yard’ behind flowers. Sometimes you can take the picture with the right settings so it’s not an issue, but this will often require blurring on part of the image. Your choice then it to either blur when you shoot or afterwards.

When the subject has edges with high contrast beside the background, that is a decent invitation to blur the background, because you can be confident it will be quick and easy to select the entire area in Photoshop.

Wand > 50 selected most of the area instantly. Quick Mask Mode showed a few spots it missed. Lasso finished the job. Note: QMM missed a few small areas. It was necessary to inspect the entire photo at 100% size to see what was omitted.

Gaussian Blur 100

Without feathering, using just what the wand and lasso had selected, a high-level Gaussian blur cleaned up the background, making the flower stand out more, and enhanced it with a soft glow around the edges.

Gaussian Blur x 12

Taking this a step further as an experiment, the background that had just been blurred once with Gaussian Blur 100, got the filter effect 12 times. (Each additional time increased the glow a little.) This extra step takes the image from a photo to fine art. It no longer looks like a realistic context.

(There were a few minor tweaks such as growing the selection +1, +2, and then +2 with a feather of +1 to deal with the fringe around part of the iris).

A dozen more shots of the same filter on a copied layer applying GB in the last dozen applications, after continuation of the same approach, and most all the fringe along the edge of the top white part of the iris has been removed. Furthermore, more of the green stems have been replaced with purple from the flower, accentuating the subject.

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