DPP Home Software Image Processing The High Pass Filter

Wednesday, April 22, 2009

The High Pass Filter

In the ongoing search for new techniques that will give your images a unique look and set them apart from the competition, the High Pass Filter can be another valuable tool for your business


This Article Features Photo Zoom

Without getting technical (or too obsessive about comparisons), think of a JPEG file in broad terms as a ready-made tuna mix used in a cafeteria sandwich. All the ingredients are pre-combined and ready to go. Separating individual components within the mix isn’t a possibility, and further additions or changes to the mix probably will produce a heavy-handed result.

Here’s the High Pass Filter process, step-by-step:

high passStep 1) In the pull-down menu, choose Layer > Duplicate Layer. The layer box opens. You’ll see two layers—Background copy = top layer, Background = bottom layer. Turn off the top layer (the copy layer) by clicking the Eye icon. Select the bottom layer by clicking on Background (it will turn blue).

Step 2) From the pulldown menu, choose Filter > Other > High Pass. In the High Pass box, set Radius to about 75 pixels and
click OK. Jump Off Point #1—Return here to explore Radius.

Step 3) Return to the Layers box (it should still be open). Turn on the top layer (select Background copy and click on the Eye icon). Using the Mode bar, choose Overlay. Watch the new image leap off the screen! Jump Off Point #2—Return here to explore Opacity and Fill.

Step 4) Save the layered file to allow return for future adjustments.

Step 5) From the pull-down menu, choose Layer > Flatten Image to combine both layers.

Step 6) Save as a copy to avoid losing the layered file. As you can see, the process for using the High Pass Filter is straightforward, but the resulting images are most certainly not. Once you’ve come up with an image you like, try creating different variations. On these pages, you’ll find some possible ways to further manipulate your finished product.


In contrast, a RAW capture is a freshly made sandwich at a four-star restaurant. Fresh ingredients are placed individually on the chef’s countertop. The chef may use his or her creativity to modify any or all of the ingredients and then combine them in ways that aren’t possible in the cafeteria. The finished product is plated in its original, plump size. Of course, both processes turn out a tuna sandwich, but their respective values and attributes are likely to be significantly different. JPEG files are relatively inflexible, particularly with regard to altering exposure. They also heavily compress color data and thus can exaggerate subtle colors and tones like skin or other fragile elements, especially during editing.

 

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