The Business of Boudoir »

Frequency Separation in boudoir retouching

Frequency separation: You hear this phrase all the time in the retouching world, especially when describing how to retouch skin. Frequency separation is not the most intuitive technique, but when you get a handle on it it can be used for way more than just retouching skin. It’s more accurate then just blurring skin as it allows you to retain details. It is also useful for fixing wrinkles, blotchy skin tones, tan lines and even clothing issues. You can run Frequency Separation on any file, RAW or JPEG, however, you get the most benefit working on a non-compressed file.

In a nutshell, this technique involves splitting your image in Photoshop into two unique layers, and through a combination of effects and layers and blending modes, you still see your original image. However it is now comprised of a High Frequency layer (think texture and skin pores) and a Low Frequency layer (Color tones). dave-doeppel-highlowfreqPIN

I would typically do Frequency Separation after I have done initial color correction and possibly a first pass of cleaning blemishes and other marks that are easily fixed with one of the Healing Brush tools or Clone Stamp.

Two Different Methods of Frequency Separation

There two methods for creating the separation layers.

  • High Pass—This is probably the more common method of Frequency Separation. However according to retouching expert Julia Kuzmenko, this method can be inaccurate because it skews data in the highlight areas. You duplicate your image and apply a High Pass Filter to the top layer and a Gaussian Blur to the lower layer. You change the Blending mode on the top layer to Linear Light.
  • Apply Image—Same as High Pass, you need two copies of your image. The lower layer you apply a Gaussian Blur and then the High Frequency layer gets processed using Apply Image and depending on whether your image is 8 bit or 16 bit  there are different settings to apply in the dialog box. 16 bit has far more color depth than an 8 bit image although one you go to 8 bit you can’t go back to 16. Do you need to know why? Well it’s complicated math so who cares, just know it works.

How to do a High Pass Frequency Separation

Let’s start with a simple High Pass Frequency Separation.

  1. Create a duplicate of your image. Either drag the background layer onto the New Layer icon or type Cmd-J(Mac) or Ctrl-J(PC)
  2. Select the new layer in the Layers palette and rename it to High Frequency, rename by double clicking on the name in the Layers panel
  3. While the layer is selected, run the High Pass Filter under Filter>Other>High Pass
  4. Now you need to adjust the Radius slider.  This is the tricky part. You do not want to see large areas of color and also you don’t want to lose details. Every image will be different. Note the Radius number so you can use it in the next layer. 2015-02-19_0002PINNOTE: Every image is different, so experiment with different numbers
  5. In the Layers panel set the Blending Mode to Linear Light and the layer opacity to 50% dave-doeppel-hp-linearlightPIN
  6. Turn off the visibility of the High Frequency layer by clicking the eyeball icon in the Layers panel.
  7. Create a duplicate of your image. Either drag the background layer onto the New Layer icon or type Cmd-J(Mac) or Ctrl-J(PC)
  8. Rename that new layer Low Frequency
  9. Apply a Gaussian Blur under Filter>Blur>Gaussian Blurdave-doeppel-hp-gaussianPIN
  10. Enter the same number here that you used for the High Pass Radius
  11. Turn the visibility back on for the High Frequency Layer

At this point your image should look like your original image but you will have 3 layers, High Frequency, Low Frequency and the original image. You can turn off the Background layer as its only there as a backup. dave-doeppel-hp-lowfreqPIN

 

How to do an Apply Image Frequency Separation

We will now do the same setup using the Apply Image Frequency Separation method. We are starting over at this point as this is a different technique, so just start with your original image.

  1. Create a duplicate of your image. Either drag the background layer onto the New Layer icon or type Cmd-J(Mac) or Ctrl-J(PC)
  2. Select the new layer in the Layers palette and rename it to High Frequency, rename by double clicking on the name in the Layers panel
  3. Turn off the visibility of the High Frequency layer
  4. Create a duplicate of your image. Either drag the background layer onto the New Layer icon or type Cmd-J(Mac) or Ctrl-J(PC)
  5. Select the new layer Rename it to Low Frequency
  6. Apply a Gaussian Blur under Filter>Blur>Gaussian Blur
  7. Adjust the radius until there are no details, only large color tonal areas dave-doeppel-gbPINNOTE: Every image is different, so experiment with different numbers
  8. Turn the visibility back on for the High Frequency Layer
  9. Check the bit depth of your image by selecting Image>Mode from the Menu dave-doeppel-ai-bitdepthPIN
  10. Select the High Frequency Layer and then select Image>Apply Image from the menu.
  11. For an 8-Bit Image use the following settings:
    1. In the Layer box choose the Low Frequency layer
    2. Uncheck Invert
    3. Blending Mode to Subtract
    4. Scale to 2
    5. Offset to 128 dave-doeppel-ai-applyimage8PIN
  12. For a 16 bit Image us the following settings:
    1. In the Layer box choose the Low Frequency layer
    2. Check Invert
    3. Blending Mode to Add
    4. Scale to 2
    5. Offset to 0 (zero) dave-doeppel-ai-applyimage16PIN

One more bit of housekeeping. You can put these two new layers into a group, then you can adjust the opacity of the entire effect. Select both High and Low Frequency layers (use cmd or ctrl to select them) then Cmd-G or Ctrl-G will create a group with both layers. You can name the group Frequency Separation.

Now, retouch your photo

At this point it is up to you where you want to start retouching: on the High or Low Frequency layer. I usually bounce between them. Sometimes I even merge the layers and run another round of Frequency Separation. You can experiment with different values for the Gaussian Blur or High Pass filter to see what effect it has. You may want to just focus on one particular area in one round, and then create another FS group to work on another part of the image just to keep them separate and you can then adjust them individually.  The key here is what tools to use on each layer and how to use them.

  • On the Low Frequency layer—You want to work on this layer using very soft and low opacity tools. If you use tools like the Healing Brush or Clone Stamp, make sure they are set to Current Layer and that the tool is very soft. I actually use the Brush tool a lot on this layer, very soft brush with low opacity and flow, I sample the color frequently using the *I* key and just brush in to smooth out tones.
  • High Frequency—This layer requires a harder higher opacity tool so you don’t end up blurring things too much. I don’t use the Brush tool on this layer but will bounce between the Clone Stamp, Healing Brush and even the Patch Tool. Make sure your tools are set to Current Layer as well.

In the Before/After example below I circled the areas that I want to fix. Mostly some highlights that I want to even out. 2015-02-16_0002PIN

I took advantage of having the separated layers in a group and lowered the opacity to blend it in with the original a bit.dave-doeppel-ai-groupedPIN

The result is a bit more natural looking with the shine greatly reduced. after2PIN

The image below was run through Portraiture. Now I love Portraiture but as you can see it does not fix the highlights that I removed or lessened in the above image.

dave-doeppel-portraiturePIN

Make It Easy

retouchpanelPINDon’t want to go through all this steps on every image? No worries, there are tons of Photoshop Actions out there that will handle this for you. I started using the RA Beauty Retouch Panel. Not only does it give you one button access to both of these Frequency Separation techniques, it gives you some other goodies as well like Dodge & Burn, Magic Eyes, Magic Smile (I use these last two on almost every image) and they also have a free panel called Pixel Juggler with some handy workflow actions. Note: I purchased these tools and am not affiliated with them.

More Info

The Retouching Academy is one of my favorite resources for retouching education. I highly recommend it. It’s run by some of the best retouchers out there, Julia Kuzmenko McKim and Pratik Naik.

Dave Doeppel

Dave is the owner of LA Pinups, specializing in Pinup and Boudoir Portraits in Los Angeles. He has always been a fan of Pinup and Burlesque. He is also an Adobe Certified Expert in Lightroom 4/5 and Photoshop CC and loves teaching photographers how to manage their images efficiently from ingesting through export.

More Posts - Website - Twitter - Facebook - Pinterest - Google Plus

FacebookTwitterPinterest

Your email is never published or shared. Required fields are marked *

*

*

UA-50586612-1