How to Use the Frequency Separation Technique in Affinity Photo

Overview

Frequency separation is a technique used in photo editing to separate two different types of image data: high frequency detail and low frequency color. High frequency detail includes things like skin texture, individual hairs, and other small details. Low frequency color includes things like skin tone and color cast. By separating these two types of data, you can make changes to each independently. This can be useful for things like removing blemishes or wrinkles without affecting the overall skin tone, or lightening or darkening the color of an image without affecting the high frequency detail.

Step 1: Duplicate the Background Layer

The first step is to duplicate the background layer. This is so that you have a separate layer to work with for the high frequency detail and another layer for the low frequency color. To duplicate the background layer, go to the Layer menu and select Duplicate Layer.

Step 2: Apply the Gaussian Blur Filter

Next, apply the Gaussian Blur filter to the duplicate layer. This filter will blur the high frequency detail, leaving the low frequency color intact. To apply the filter, go to the Filter menu and select Blur > Gaussian Blur. Use a radius of around 5 pixels. You may need to experiment with this value to get the best results.

Step 3: Apply the High Pass Filter

Now apply the High Pass filter to the background layer. This filter will do the opposite of the Gaussian Blur filter and will sharpen the high frequency detail while leaving the low frequency color intact. To apply the filter, go to the Filter menu and select Other > High Pass. Use a radius of around 5 pixels. Again, you may need to experiment with this value to get the best results.

Step 4: Change the Blending Mode

Now that you have two layers with different types of image data, you need to change the blending mode of the top layer so that you can see the effect of the filters. To do this, go to the Layer menu and select Blending Mode. Choose the Linear Light blending mode from the list. You should now see the high frequency detail on the top layer and the low frequency color on the bottom layer.

Step 5: Adjust the Opacity

You can now adjust the opacity of the top layer to control how much of the high frequency detail is visible. A lower opacity will make the detail less visible, while a higher opacity will make it more visible. For most images, an opacity of around 50% will work well. But, as with all things in photo editing, it’s best to experiment to see what looks best for your particular image.

Step 6: Edit the High Frequency Detail Layer

Now that you have the high frequency detail layer isolated, you can make changes to it without affecting the low frequency color layer. This can be useful for things like removing blemishes, wrinkles, or other imperfections. Simply use the Healing Brush or Clone Stamp tool to make the desired changes. When you’re finished, you can adjust the opacity of the layer again to control how much of the changes are visible.

Step 7: Edit the Low Frequency Color Layer

Now that you have the low frequency color layer isolated, you can make changes to it without affecting the high frequency detail layer. This can be useful for things like changing the overall color of an image or removing a color cast. Simply use the Hue/Saturation or Color Balance tool to make the desired changes. When you’re finished, you can adjust the opacity of the layer again to control how much of the changes are visible.

Step 8: Merge the Layers

Once you’re happy with the changes you’ve made to both the high frequency detail layer and the low frequency color layer, you can merge the two layers back into one. To do this, go to the Layer menu and select Merge Layers. This will create a new layer that contains both the high frequency detail and the low frequency color. You can now adjust the opacity of this layer to control how much of the changes are visible.

Step 9: Save the Image

The last step is to save the image. To do this, go to the File menu and select Save. Choose a file format and location, then click Save. That’s it! You’ve now learned how to use the frequency separation technique in Affinity Photo.

Now that you have your images separated into low and high frequencies, you can start to work on each one independently.

On the low frequency layer, you can use a clone stamp tool to remove any blemishes or unwanted objects. The clone stamp tool copies pixels from one area of an image to another, so you can use it to cover up unwanted details.

To use the clone stamp tool, select it from the toolbox, then click and drag on the area you want to copy. As you drag, you’ll see a crosshair appear. This is the anchor point, and the clone stamp will copy the pixels around this point.

Release the mouse button, then click and drag again to start painting with the cloned pixels. The clone stamp tool works best if you use a soft, round brush.

On the high frequency layer, you can use the eraser tool to soften wrinkles or other imperfections. The eraser tool will erase whatever pixels you paint over, so be careful not to erase any details that you want to keep.

You can also use the brush tool to paint over areas that you want to keep. The brush tool works just like a regular paintbrush, so you can use it to add or remove color from an image.

When you’re finished, you can merge the two layers back together. To do this, select both layers in the layers panel, then click the “merge layers” button.