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Sunday, 26 February 2012

Image sharpening using High pass filter



With Photoshop, a photo can be sharpened in many ways. Some popular among them are : sharpen, smart sharpen and most popular unsharp mask. Here, I wish to demonstrate image sharpening technique I use : using a high pass filter. Its a few step process and creating action for this one is also fairly simple. Once created action, sharpening can be applied with just a click to any image in future. However, I wont be explaining here how to create actions, some other time.  :-) OK, so lets begin.

Step 1. Open the image. (layer name: background, by default)

Step 2. Duplicate the image. (layer name: Layer1, by default)

Step 3. Change the blend mode of Layer 1 to "Overlay". Blend modes can be found just above the layer panel.

Step 4. Now apply High pass filter to Layer1. Its can be found under the menu : Filter - Other -High pass.

Step 5. Set the radius value around 5. The key for correct sharpening is that one should see the edges in the thumbnail. press OK.

Step 6. Now, adjust the intensity of sharpening just by adjusting the Layer1 opacity.

Step 7. Cheers !

The images here are for demo. Changes may be  subtle to observe with images provided. Better, open them in separate window and compare them to see the effect. Ideally, advised to carry the high pass sharpening to ur own image with good resolution and observe the effect.

Before Sharpening, Butterfly species : Pea Blue

After sharpening

Few reminders:

1. Better original image provides better flexibility.
2. High pass filter improves contrast a bit.
3. This technique is well suited for photos with blurred background. As such background do not have edges, high pass filter is not applied to that part at all.

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