Hey guys welcome to a new Photoshop tutorial with PSD box I'm Andre and today I'm going to talk about advanced selections and how to use calculations in Photoshop I have this tutorial already on the website it's called calculations advanced masking and as you can see here on the screen I had the text version published I don't know where in 2010 and today.
Roland Rick mentioned that he couldn't find that tutorial on my youtube channel and when I made this tutorial about how to add tattoos and on the skin on a realistic manner I think I mentioned about calculations and actually I talked about constellations in other videos and I think I made a quick demo and on some of my tutorials but today I'm going to talk specifically about how to use calculations and how to create advanced selections and I'm going to show you an example of how you can use this a great feature of Photoshop so I hope you will like it and let's get started you.
So in order to use calculation use this free image and well actually it's not the free image I got it from deposit photos but here on the website I used a really simple image with a blue background and for an image like this calculations it's not even necessary because with a color range or with even with the magic wand tool you can you can create a selection for this it's really it's really simple so I'm going to use something a bit more complex not really difficult but as you can see here we have these branches over here and well we have this Mountains these are really easy to select but here we have some problems with the trees and making a selection with the quick selection tool or with the magic want to could take some time and using the calculation doesn't mean that it has to be something that is really quick to do but it can handle something a bit more in science example and more complex selections and then you can do with the magic one for example with the color range so it doesn't necessarily mean that it has to that it creates really quick selections but it can handle complex selections so in order to work with this first you have to go to the channels I forgot to change the language of Photoshop so hang on a second I'm going to restart Photoshop and because you will see better if it's in English okay back to Photoshop as I said you have to go to channels so here what you have to do is take a look at each of your channels and identify the area that you want to mask for this example I want to mask the sky so let's imagine I want to change the sky with something else so what I would do is and take a look at each child the red green and the blue of course we are working on the RGB color space and you have to choose the channel that gives you most contrast between the element that you want to mask and that the element that you want to keep so in this case blue is a channel that gives you most contrast behind during sky and this church here and the foreground over here in many cases maybe more than 50% of the times the blue channel will be the one that will give you most contrast but it the pan of course image that you're using so I will use the blue channel so the next thing that I'm gonna do is go to image adjustments and choose sort image.
Calculations over here now here you can see this new window appears this menu over here and we have source 1 and source 2 and now we have the blend mode so basically what calculations does is it takes two channels and uses a blend mode to to blend them and give you more. Contrast we also have the - to invert. Modes here so for example I can take the blue channel on source want you can even mask from you can even select layers from different documents so if you have different documents open you can do that and of course different layers I only have one image so that's the only source that I have so I can take the blue channel and mix it with the green channel for example and using the multiply blend mode you can see the result if I change this to for example overlay you can see what I get obviously I'm just interested in the contrast between the edges here I think I get bright tones here I don't care about that so one thing that would work here they said I found that the blue channel will give me more most contrast I will use source one to be blue I can use blue on source 2 as well but instead of using this blend mode here we get two other blend modes which are add and subtract if I use subtract you can still get this blue image because I'm subtracting blue from blue so the result is nothing now if I change this inverter any of them for example this one top one you can see how immediately I increased contrast and now I I saluted the sky a lot more and we also have isolated the details over here now we can complement this with another technique which I'll see you later after I'm done with this I'm going to add a new sky and I will show you how to blend the colors on the edges as well so the good thing about the add and subtract blend mode is that we also have the offset and the scale now with this you can do some very advanced stuff I don't know the math behind this but I know pretty much and what I have to do to get certain results basically if you're increasing the offset this goes from 0 to 255 so let's put it to the max so you can see what it does it kind of multiplies everything and the lower you have it let's move on 64 the higher the. Contrast the same with the scale so we should put a scale of 2 and this one goes from the from 1 to 2 so we kind of.
Darkened the highlights let's let's call it that way so if you put a scale of 1 and an offset of let's say 20 you can see what you get so I think 64 works and scale 1 and this is what I got I'm going to click OK and I can repeat the process go down to image calculations and this time you can see when you click OK you create a new alpha Channel and alpha channels is just a sale selection basically so I can get alpha wall and mixer I know with the red so you can experiment and with this I'm going to invert one of the channels you can invert top of the bottom one it depends on really what you want to have selected but you can see that on alpha 1 I had this white and actually I had the sky. White and I want to keep it that way so I would probably just multiply alpha Channel with itself you know apply image. Calculations so I will get alpha 1 and just multiply it by self or even choose let's try soft light to see if we can increase the contrast even more yep and there you have it now. We have some problem over here but I'm going to show you how to how to deal with that of course you can also apply levels and create two to alpha channels and I'm going to show you how to do so with alpha to selected I'm going to press ctrl + L to open my levels and I'm going to increase the highlights a bit and darken the mid-tones and one cool. Trick here is using the brush tool actually I'm sure you've seen this before so I'm going to put the opacity level to 100% but it is a soft brush and I'm going to change the blend mode of the brush itself to let say overlay and what you do with this is if you paint with white over black area with the overlay blend mode nothing will happen but if you paint on something that is mid-tone gray like for example here right now with black take a look I just brighten the brighter areas and not the dark ones like that and here as well make sure you don't paint over this area but if you can see here we have this dark line which helps us separate things so you can safely paint with this you will do some some of the edge but it's a lot better than using the magic wand so explain over there as well remember that it doesn't always have to be pure white because transparency sometimes look better semi transparent areas it also depends of course on the new background that you're going to use the image on so I'm going to paint with this over here really quick and here with black.
Actually I'm going to change the blend mode back to normal don't forget to change the blend blend mode back to normal on your brush because sometimes we can give you a headache because if you go back to the lawyers the blind mode will stay the same will be kept in in soft light or whatever mode you've had it and let's say you want to paint on a layer mask and it doesn't work and you don't know why it happened to me a lot of times okay let's ups let's fill this area over here I'm going to fast forward painting this areas over here and I'm going to show you how I can change how I will change the sky and blend the colors on the edges.
Okay I'm not going to select the top part if you check the RGB and this part is really easily selected by selectable with the quick selection tool now if you wanna check if this is pure white what you can do is grab the eyedropper tool and go to info you can see this tab if. You go to window and choose info and just move the mouse over here and CMYK if you see that if you see no change there it means it's pure white so that.
On here when where it's black the K is set to 100% okay so I'm going back to. The RGB I'm going to live alpha 2 there and well actually I'm going to create the selection I'm going to unlock the way with alt double-quick now I'm going to ctrl click the Alpha 2 and go here and create a layer mask it's inverted so I have to control I on it and you can see I selected the sky and everything there will I still have some remainings over there because I went really quick and over here but I will change the sky now I'm going to open a new image so I'm going to paint my new sky over here and it's this one this is the sky I want to use something a bit more sunset ish looking I'm going to place it right over there and I'm going to fix this part here on top now deactivate the layer mask would shift click and I will select with the quick selection tool I'm going to select this part over here maybe with.
The magic wand it's a bit quicker tolerance 13 and a bit higher okay like.
That and this area here as well and I'm.
Going to reactivate the layer mask and I'll have to invert the selection and with the brush paint on the layer mask with white to reveal this obviously I'm. Doing is really quick because what I wanted to show you really is how to work with calculations and even there went really quick and I could I could have done a selection a lot better than this but that way you can practice yourself and learn how this Tool Works now as I said if you have some remainings on the edges which is not which is perfectly normal and it's it will happen what you can do is go back to the layer mask right click.
On it and choose select and mask or refine edge or we find mask the P depends on the Photoshop version and here what I can do if I remove too many too much detail I can shoot the edge positively to recover some of the deleted parts and increase maybe the feather a bit and then choose decontaminate colors and what Photoshop will do is if you increase the fat it too much it would try to match the color of the surrounding areas I think it uses the content aware feature I'm not sure.
So I will instead of using a positive edge I'm going to leave it to zero maybe here on the shift edge and probably increase the contrast just a bit or try not changing any of the settings here and see what you get it really depends on your image but usually it works.
Pretty well what it does is it takes the colors around the edges and it blends that with the background you can also use the smart radius to just paint I never use this so I rarely use this you.
Pro have to choose the minus here and just paint like that and hope that. Photoshop will do a good work I made this really quick you can get a better edge around here but I so I'm going to click OK now and that's. How I change oops that's how I change the background I and use the calculations on this so calculations is a really powerful tool I went really quick here but I just wanted to show you that on my website you'll find a step-by-step tutorial on how to use it and well I hope you enjoyed it and if you like it just comment on the video or on my website and I'll be glad to answer any questions if I if I can help so see you next time