Frequency decomposition step by step: the essence of the method, stages, settings | Articles | Photo, video, optics

How to dis­creet­ly and effi­cient­ly remove defects from the skin, but pre­serve the tex­ture? How to accu­rate­ly align the pig­ment and uneven­ness of the face? For such tasks, sim­ple tools like a stamp or a heal­ing brush will not be enough. You will need fre­quen­cy decom­po­si­tion.

We will tell you what fre­quen­cy decom­po­si­tion retouch­ing is, how to do it effi­cient­ly, quick­ly and at the same time not turn your face into a plas­tic mask.

Fre­quen­cy decom­po­si­tion repels begin­ners because of its appar­ent com­plex­i­ty, but by mem­o­riz­ing the algo­rithm, you will mas­ter the most pow­er­ful and one of the fastest skin work­ing tech­niques / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Photosklad.Expert

What is frequency decomposition in Photoshop

Fre­quen­cy decom­po­si­tion retouch­ing is when a pho­to is decom­posed into sev­er­al fre­quen­cies using a spe­cial algo­rithm. Usu­al­ly the pic­ture is divid­ed into two fre­quen­cies — upper and low­er.

The upper fre­quen­cy is respon­si­ble for the details and tex­ture. These include pim­ples, wrin­kles, small scars, moles, indi­vid­ual hairs, black dots, dust, crum­bling mas­cara. The low­er fre­quen­cies are the cut-off pat­tern and col­or. They are respon­si­ble for the shape, large ele­ments of the pic­ture.

Visu­al­iza­tion of high and low fre­quen­cies. On the left — high fre­quen­cies, tex­ture, on the right — low fre­quen­cies, chiaroscuro / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photosklad.Expert

Hav­ing decom­posed the pho­to into two fre­quen­cies, the pho­tog­ra­ph­er works sep­a­rate­ly with fine tex­ture and chiaroscuro. This allows you to gen­tly smooth the skin, but leave pores; remove pim­ples, but keep the col­or intact.

How to do frequency decomposition

In fre­quen­cy decom­po­si­tion skin retouch­ing, it is incred­i­bly impor­tant to fol­low the exact pro­ce­dure, not to skip any of the steps. Ini­tial­ly, it seems dif­fi­cult, but after 5–10 rep­e­ti­tions with an out­line at hand, the process is remem­bered.

Stages of frequency decomposition. Layer preparation

1. Make two copies of the orig­i­nal lay­er.

To do this, right-click and click Dupli­cate Lay­er / Dupli­cate Lay­er. Faster option — key­board short­cut Ctrl+J. You need to do this twice. The top lay­er will be for high fre­quen­cies, tex­tures, the bot­tom one — for low fre­quen­cies — chiaroscuro.

To bet­ter nav­i­gate, dou­ble-click on the lay­er names and rename them. Call it that — high fre­quen­cy and low / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photosklad.Expert

2. Devel­op low fre­quen­cies.

— Turn off the vis­i­bil­i­ty of the high fre­quen­cies lay­er — click on the eye icon to the left of the lay­er.

– Click on the lay­er with low fre­quen­cies.

Click on the eye icon to turn off the vis­i­bil­i­ty of the lay­er. After that, stand on the lay­er with low fre­quen­cies to start work­ing with them / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photostore.Expert

— Apply a fil­ter to it Blur Gauss­ian / Guass­ian Blur.

You can find it at the top of the menu. Fil­ter / Fil­ter — Blur / Blur — Gauss­ian Blur / Guass­ian Blur.

Where to find the fil­ter Gauss­ian Blur / Guass­ian Blur for blur­ring low fre­quen­cies / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photosklad.Expert

– Select the blur radius.

It is nec­es­sary that small details dis­ap­pear on the skin, and you could not see the tex­ture — pores, indi­vid­ual hairs, fine wrin­kles / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Photosklad.Expert

The larg­er the face in the frame, the larg­er the radius val­ue. Usu­al­ly this range is from 3 to 20 pix­els. Blur group and full-length por­traits, where the faces of the mod­els are small, blur by about 3–5 pix­els, and por­traits, where the entire space of the pho­to is occu­pied by the face, by 15–20 pix­els. These num­bers are not an axiom, but a con­ve­nient start­ing point for your own exper­i­ments.

3. Devel­op high fre­quen­cies.

– Turn on the vis­i­bil­i­ty of the high fre­quen­cy lay­er.

‑Place on the lay­er with high fre­quen­cies by click­ing on it with the left mouse but­ton.

To enable lay­er vis­i­bil­i­ty, bring back the icon with the eye in the red cir­cle. Which lay­er you are cur­rent­ly on is shown by its col­or. The active lay­er — with the upper fre­quen­cies — is now dark gray / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Photosklad.Expert

– Open Image / Image — Exter­nal Chan­nel / Apply Image.

Here we will “pull out” the tex­ture on the lay­er with high fre­quen­cies. To do this, a blur­ry lay­er with low fre­quen­cies is sub­tract­ed from the source.

Where to find the Exter­nal Chan­nel / Apply Image func­tion in Pho­to­shop / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Fotosklad.Expert

Only one thing is impor­tant here — set the fol­low­ing set­tings:

- in the tab Lay­er / Lay­er select the low-fre­quen­cy lay­er you blurred (anoth­er rea­son it’s good for a begin­ner to rename lay­ers).

To sub­tract low­er fre­quen­cies from a lay­er with high fre­quen­cies, you need to select a blurred lay­er in the Lay­er / Lay­er / drop-down list.

- For 8‑bit mode: Over­lay / Blend­ing — Sub­trac­tion / Sub­tract. Scale / Scale — 2. Shift / Off­set — 128.

Fre­quen­cy decom­po­si­tion set­tings for 8‑bit mode / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Fotosklad.Expert

If the image turns grey, don’t wor­ry! So be it. So you are on the right track.

- For 16-bit mode: Over­lay / Blend­ing — Adding / Add. Scale / Scale — 2. Shift / Off­set - 0. check mark Invert / Invert.

Fre­quen­cy decom­po­si­tion set­tings for 16-bit mode / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Fotosklad.Expert

– Press OK or key Enterto apply the set­tings.

To under­stand what bit­ness your pho­to has, look at the num­ber in brack­ets next to the title / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Fotosklad.Expert

— Put the gray lay­er with high fre­quen­cies in over­lay mode Lin­ear Light / Lin­ear Light.

After apply­ing Lin­ear Light / Lin­ear Light, the pic­ture should look like the source looked when you first opened the file. This means that you have decom­posed the pho­to into fre­quen­cies cor­rect­ly / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photosklad.Expert

Frequency Decomposition — Instrument Settings

In fre­quen­cy decom­po­si­tion, work goes on alter­nate­ly with two fre­quen­cies. You can con­stant­ly switch between lay­ers, or retouch in stages — first, a com­plete clean­ing of pim­ples, hairs, and then edit­ing chiaroscuro. The order is not fun­da­men­tal. It is impor­tant not to con­fuse the tools and lay­ers on which you are work­ing.

For retouch­ing, we will use the tools Clone Stamp Tool, Heal­ing Brush Tool and Mix­er Brush Tool. Read more about how these tools work in the text about basic retouch­ing.

Treble instrument settings

On the tex­ture retouch­ing lay­er (pim­ples, wrin­kles, scars, hair), you can work with two tools:

• Stamp / Clone Stamp Tool.

Stamp set­tings for fre­quen­cy decom­po­si­tion / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Fotosklad.Expert

• Heal­ing Brush / Heal­ing Brush Tool.

The main thing, as well as for stamp- in the drop­down list Sam­ple / Sam­ple choose Cur­rent Lay­er / Cur­rent Lay­er.

This is nec­es­sary in order for the tool to take a patch from the lay­er on which it is locat­ed, with­out using the lay­ers below it. Oth­er­wise, the patch will be strong­ly knocked out in col­or. Oth­er­wise, you can leave the default set­tings.

This is what hap­pens if you do NOT put the Cur­rent Lay­er set­ting in the Sam­ple col­umn. This is true for both the Stamp and the Heal­ing Brush. For retouch­ing to work, set Cur­rent lay­er / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photostore.Expert

Secrets of frequency decomposition: working on a layer with high frequencies

• The size of the brush should match or be slight­ly larg­er than the defect.

You don’t need to mea­sure the brush radius pix­el by pix­el to match the pim­ple or hair thick­ness, but it’s also hard­er to work neat­ly if the patch is much larg­er than the flaw.

• Look for areas with sim­i­lar tex­tures to patch.

Skin has dif­fer­ent tex­tures on dif­fer­ent parts of the face. For exam­ple, the skin under the eyes is more del­i­cate and thin than on the cheeks. Visu­al­ly, the skin on the fore­head and on the nose also dif­fer from each oth­er. To make the retouch­ing invis­i­ble, look for a patch near­by. If you are retouch­ing the cheek, sam­ple the stamp or repair brush from the cheek as well.

• Take patch­es from areas with the same bright­ness.

For exam­ple, if you try to trans­fer a patch that you took from a skin area in the shad­ow to a high­light, a dis­crep­an­cy in tex­tures will catch your eye.

Here’s what hap­pens if the patch does­n’t match in bright­ness and tex­ture / Illus­tra­tion: Eliza­ve­ta Lentchevicha, Photostore.Expert

Instrument settings for low frequencies

To even out chiaroscuro, smooth out age spots, you need to stand on a lay­er with low fre­quen­cies and use the tool Mix­er Brush Tool.

Mix­er Brush Tool is an attempt by the devel­op­ers of Pho­to­shop to mim­ic the effect of a reg­u­lar brush in real­i­ty when an artist paints on paper. It trans­fers col­or from one area of ​​the pic­ture to anoth­er in strokes, and also mix­es col­ors togeth­er, as if you were try­ing to mix two col­ors on a palette.

Mix brush set­tings for fre­quen­cy decom­po­si­tion. If you want the effect to be stronger, adjust only one para­me­ter — Pres­sure / Flow / Illus­tra­tion: Eliza­ve­ta Chechevit­sa, Fotosklad.Expert

Principles of working with a mix brush in frequency decomposition

If the com­plex­ion needs to be smoothed out, move the brush in small cir­cu­lar motions. This way the col­ors will blend.

If the task is to cor­rect or extend the shad­ow, slight­ly light­en the bruis­es under the eyes, then you need to work with strokes, trans­fer­ring the col­or from one part of the pic­ture to anoth­er.

The mix brush is a pow­er­ful tool with which you can eas­i­ly “kill” the anato­my of the face. For exam­ple, it should be remem­bered that the most con­vex parts of the face (fore­head, nose tip, chin, nose col­umn, cheek­bones) should be lighter than every­thing else. Shad­ows lie under the cheek­bones, under the low­er lip, under the jaw.

Anoth­er secret — in no case should you com­plete­ly remove the nasolabi­al fold. To avoid this, con­stant­ly look at the chiaroscuro source. This will help you notice unnat­u­ral­ness in time and go back a cou­ple of steps.

After retouch­ing by fre­quen­cy decom­po­si­tion, the result may seem too strong — the skin in such cas­es seems “plas­tic”, too smooth. In this case, add lay­ers to the group (illus­tra­tion below) and low­er the opac­i­ty of the result­ing fold­er. Then the nat­ur­al tex­ture will show through the retouch­ing. With prac­tice, you will resort to this less and less — learn how to care­ful­ly retouch with­out over­do­ing it.

To add lay­ers to a group, click on them while hold­ing Ctrl, and then on the fold­er icon. Click on the fold­er and low­er the opac­i­ty using the Opac­i­ty slid­er