How To: Properly Use and Understand Frequency Separation

hey my name is Steve Walter and today I wanted to make a video about frequency separation hold on hold on I know we've got plenty of those on the Internet Steve why do we need another one and it's that reason right there the why that's the purpose for today's video I want to explain to you guys why you would use a 16-bit image over an 8-bit image and why you use the settings you use for a 16-bit versus an 8-bit image and I should mention that in doing this process we're gonna recreate frequency separation for a 16-bit image in two different ways and we're gonna create it for an 8-bit image in two different ways using the same settings for both and I want to show you the differences between all four of them okay I'm not actually gonna be doing any retouching today I'm just gonna be breaking down and explaining frequency separation and let's do just that break down the term frequency separation you're separating frequencies and what frequencies are we separating the highs and the lows now without getting real technical right when you talk about wavelengths and things like that we don't need to get into that let's talk about it as photographers what's high and what's low high is texture eyelashes hair freckles pores things like that texture that's our high frequency our low frequency color that's the way I break it down to my mind and that allows me to wrap my head around this process of what's happening taking your original image pulling out the color and pulling out the texture so here I have a portrait that I took recently of a model this is had a she's fantastic this is my background layer I'm gonna leave that there as a constant but what I want to do is I want to duplicate this layer twice Y twice because I need two layers one where I can create my color and one where I can create my texture so let's do that the way that I like to duplicate my layers is command J hit it twice there we go layer 1 layer 1 copy I'm gonna rename these layers just so that we're a little bit more organized if I double click on the title I can rename that we're gonna call this lo color double click here hi Tex so this is going to be my color layer this is going to be my texture layer so I'm gonna hide the texture layer for a second so that we can see what's going on on this layer and what we need to do in order to create this as just color is we need to remove the texture we basically need to make this just colors and not any texture so the way that you do that is by using some type of blurring method the most common blurring method that I see people using is Gaussian blur Gaussian blur however you want to pronounce it really you could use any kind of blur you want I'm gonna use Gaussian blur specifically so that that way it's consistent with some of the other information that you've seen out there so we're gonna go up to the filter menu blur and choose Gaussian blur Gaussian blur sorry I'm gonna be saying that differently each time the point of this blur again is to remove texture I'm gonna zoom in a little bit here and what we want to do if I slide this all the way over here so I have point 1 blur which is almost no blur you can see the texture on her skin now you can see the texture on the hair as you can see the texture and her eyebrows or eyelashes remember that's our high frequency and we want to eliminate that because this is the layer that we're creating for just our color our low frequency so I'm gonna start sliding that up until details and textures start to go away when I slide and let go it actually renders it and here's what I'm looking at specifically her birthmarks her beauty marks on her chin over here on her cheek I want to make sure those are completely gone and why do I want to do that specifically on this image because I want to make sure those are not being touched when I start manipulating my color right I want to make sure those are preserved on the texture layer and I will be sure to not retouch them out because that's a part of her that's her personality that's her character so I'm gonna blur this until those go away and it looks like maybe around okay they're almost there let's hit let's just do a nice round 5 because I'm neurotic or an odd 5 because I'm neurotic four point seven to me is like I need it to be flat so here we go five and those beauty marks are gone so if I uncheck this preview it will show me the original and then here's what it looks like blurred perfect I can probably go a little bit higher but I think that's good enough typically when doing frequency separation you want to use a lower blur possible because when you start cranking the blur all the way up over here you can see that now if this was my color layer it's a mess everything has sort of been unified into one almost one color so I want to have a lot of options for my colors but I don't want it to be too blurry like this so I hope that explains why you wouldn't use a super large radius in this case five is getting us right where we need to be we're gonna use the constant radius of 5 in our blur for every time we do it so I'm gonna say okay great now I need to show my texture layer which at this point is still just a duplicate of our original now I need to go to image apply image and if you think about that what we're doing is we're applying a layer an image to this texture layer now which layer are we applying we're applying our color layer and if you start to break that down you're applying it right when I think of applying I think of adding what we're actually doing is we're sort of extracting right we're extracting the color by applying the color layer to the texture layer we're extracting that color and then we're gonna be left with just the texture so we've already made our color layer and now what we're doing is we're taking that color layer and extracting it from the texture layer leaving just the texture and just our color then we're gonna blend those two together so that we can see them as we would want to in our original image so I need to target that by going to the layer let me move this window up a little bit higher here go to the layer and that's why I named it low color because that tells me real easily what layer I'm looking for so the settings that I want to use I need to make sure my channel RGB leave that alone here are the things that we're gonna change we're gonna make sure that invert is checked we're gonna then make sure our blending is set to add so when you think about that we're adding but we're inverting that so we're kind of subtracting it kind of kind of opacity leave that alone scale set to 2 that's what I want preserve transparency leave that alone mask leave that alone offset set to 0 so the main key points that I want here is to make sure that I have my color layer targeted I have the box checked for invert by blending is set to add my scale is set to 2 my offset is set to 0 this is what you would use if you were using frequency separation on a 16-bit image and again I'll explain why so let's say ok so this renders it and it still looks like a gray layer but if you look at this layer let's break this down for a second to is that this neutral gray is kind of across-the-board everywhere let me zoom out and then what we're left with is that texture and what is texture texture is contrast when is contrast contrast is hi brights and low darks so it's bright and dark that's really all texture is so this is our high-frequency layer now what we want to do is basically eliminate all of that gray and we do that by using a blend mode in this case linear light so linear light says take that grayish layer and basically make that gray transparent but leave the brighter parts and the darker parts there so that combined with our color layer should give us our original image but how do we know for sure that it's the original image well the way that I check it in the way that I test it is by setting up color sample points so I'm gonna show you how we do that but first I want to select both of these and I'm gonna group them together I'm gonna name this ad or I'm gonna name it ad slash checked why am i naming it that well because if you recall we use the blend mode of ad not subtract and we made sure that our box invert was checked so that's why I'm naming it that way so that way we can kind of keep track of everything here I'm gonna hide that for a second what I want to do now is I want to set up some control points I want to set up some color points that we can test our settings against so in order to do that I want to create a threshold layer I'm gonna make an adjustment layer here threshold and I want to find the brightest part of the image and the darkest part of the image and set points there so how do we set those points we need to set those points with a tool it might be hidden somewhere in your tool bar but it's the color sample or tool and if you want to use the keyboard shortcut to get there hit the letter I now if it doesn't show up immediately if you hold shift and press I you want to keep cycling through these tools until you see this guy it looks like the eyedropper plus a little target so now what I want to do is I'm gonna find the darkest part and the lightest part so you can see this threshold layer just basically gives me an image of black and white just values of black and white so if I go all the way over here you see the image is black unless I start sliding to the left I can start to see the brightest parts of the image so here if I slide over just a little bit there we go at threshold level 249 I can start to see the brightest parts of the image and that's what's gonna tell me is is this white or is this almost white so I'm gonna zoom in here and I'm gonna set a sample point right here boom and you can see that's been rendered right here I want to make sure my info window is open and then number one this is the value for number one good now I'm gonna go all the way the other way zoom back out and start pulling in you can see I don't even have to start pulling in I already have a black value or close to a black value over here and again does this need to be exactly black or white nope I just want something that I can have a measurement against so I'm done with my threshold layer I no longer need it I just needed it to show me the brightest part and the darkest part so I can now delete that I'm gonna zoom back out and what I'm gonna do is I think I'm gonna set two other points maybe one other point over here maybe say in her forehead and then oh I don't know maybe one here in her lips so what I've done is I've just set up four control points I've set values number one and number two are the primary three and four just kind of there for me to see is there a shift in color because you can see number two is zero zero zero no information it's black so number two over here on the back of her head that's black you can see for number one it's not quite white because white is 255 so it's just under white so there's no pure white in this image but close enough for us to see is there any change and now where will I see that change I will see that change when I show this layer here and when I show it there's actually no change and that's what we want we don't want to see any change we want this to be exactly what we had from our original image and that's why you use the settings you use for a 16-bit image and that's why I recommend using a 16-bit image because what we're gonna do right now is we're gonna use the other settings for the 16-bit image and see is it close enough and then we're gonna do the same thing for an 8-bit image so let's do that now in this case what I'm gonna do is save a little bit of work because we already established that the color layer was going to be a 5 pixel blur on is gonna duplicate that command-j duplicate sit command shift right bracket moves it all the way up to the top I'm gonna duplicate my background layer because I need that to render another frequency separation move that up to the top - we're gonna rename this high-techs copy so it's consistent and then we're gonna go to image apply image and now what we're gonna do is we're gonna use the other group of settings so what are they well we still need to target our color layer here we go and now I'm going to uncheck invert because right now it's leaving the settings that we had from before which we know are good we don't want those this is the experimentation this is the Y this is the science behind this type of stuff so I'm gonna uncheck this I say science like I'm some type of scientist but I'm just a photographer not just a photographer I'm a photographer so subtract and notice what happened was the offset was automatically adjusted for us when we moved from add to subtract Photoshop said oh yeah we got to set the offset to 128 and these are the settings that you commonly see use for an 8-bit image okay but if we look at the image right here just visually if I look at this it looks exactly the same as what we had before there's almost no difference right so I'm gonna say okay to this and I'm gonna change the blend mode to linear light and there we go if I now hide this the original one that we had the ad checked and you know before we do that let me group these and let's call this subtract unchecked you can see I'm abbreviating here because that's what the kids do with this group selected here's our background this is our original I'm hiding the good version if I now hide this let's see if our values change they do you see that let's look down at the info panel right now this is our original image there was no information in our black zero if I show this you see that shift it's tiny it's so small but it's a shift and even if I look at the image visually before and after I can see that black value goes up just a tiny little bit so visually I can even see it on screen but for sure right here with a measurement with that target dropper tool I know for sure that there was a change so that's what tells me these settings are no good for 16-bit image so if you are using the subtract method or the unchecked method for a 16-bit image stop doing that don't do it anymore if you know people that are doing it send them this video tell them don't do it anymore and they might say well why the reason why you want to do that is so that you have an exact copy of your original image you don't want to lose any pixel information no data at all great I hope I've hammered that home enough now let's do this with an 8-bit image I'm gonna take this image will render it as an 8-bit will keep our settings where they are as far as the target sample points but we're gonna redo the frequency separation using both of those settings that we had before so to do that I'm going to just select both of these delete them here we are left with our background layer to turn an image from 16-bit to 8-bit you go up to image mode 8-bit boom just like that now what we're gonna do is we're going to render frequency separation command J twice we're gonna name this low color so I'm repeating the same steps we did so this part we can kind of zoom through a little bit cuz I already had all the explanations so I'm just gonna kind of do this filter blur Gaussian blur that's gonna give us that five points boom show this this is our high Tex image apply image so we're gonna do the first way that we did it which was add checked so I need to target my color we need to check invert we need to set the mode to add boom there we go done okay let's do it again duplicate my color move it up to the top duplicate my background move it up to the top rename this to high Tex copy image apply image target the copy layer uncheck invert set this to subtract it should automatically and it does move it to 128 say okay so this we are going to group we're just gonna call this sub this we are going to group and we are going to call this ad Oh what we didn't do set these to linear let's do that blending mode linear I got ahead of myself there I got excited boom linear okay so then I collapse these groups we're gonna hide them so remember the ad method the checked method is what I recommend and for reason you use on a 16-bit image so the recommendation for an 8-bit image is the inverse of that the subtract method right where you uncheck invert set the blend mode to subtract and then the offset is at 128 scale is still 2 now remember we want to look on our color and see is there any shift cuz right now here is our base settings and when we show this look at that there's a shift same shift we had before it moves the color space just a little bit the tiniest amount the smallest amount so that means it's not 100% well let's see if the add method does anything let's show that and you can see it also shifts so I hope that you guys can see the difference there between the 8 bit and the 16 bit image and what's the main takeaway what should be the main takeaway right basically how am I going to title this video it's that if you're using frequency separation you should 100% use a 16 bit image because as we've discovered through science there is no change to your image at all if you use the settings checking invert add scale of 2 offset of zero if you use those settings your image is exactly the same if you use any other settings and any other bit depth it won't be 100% so if you want to have a 100% fully accurate frequency separated image use the settings that I've described used a 16-bit image I hope this was helpful I hope you enjoyed this I hope this isn't just another frequency separation video and if this is one that you think is going to be different share it share with the blogs let them know that Steve showed me how to properly do frequency separations so maybe that's it how to properly do frequency separation that's gonna be the title that's the clickbait if you guys watched I got some of the other stuff that I'm doing head over to my Instagram at Steve Walter photo I also have a podcast if you want to check that out of course I have a podcast everyone has a podcast it's also Steve Walter photo super original title but you can find that on iTunes SoundCloud even here on YouTube I record the videos in my studio if you guys have questions comments feedback please share with me I hope you guys are using 16-bit images for your frequency separation and maybe in another video I'll show you the process that I go through using the median blur and how I actually go ahead and retouch an image so until the next one bye see ya [Music]

Channel: Steve Walter Photo

Views: 18,467

Keywords: Frequency Sepration Explained, Frequency Separation, Retouching, retoucher, retouch, portrait, FS, photoshop, adobe, photography, photo, science, lesson, howto, tutorial, explination

Id: xzVNy015VrI

Length: 17min 55sec (1075 seconds)

Published: Fri Jul 06 2018