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in this final exercise we're gonna take , a look at the issue of bit dept hand the , W-bit per channel mode inside of , Photocopy I'm working on different , image imagine that called colorful face , DTP it's found inside of the O , hello channels folder and it's another , image from that same photographer Sophia , Si backhand notice the title bar here , this ugly blue windows title bar it says , slash eight notice it says Backslash , eight and it would say the same thing on , your bedevilment's title part as , Welland what that's telling us is that , we are looking at an image that contains , eight bits of data per channel and that , means that we have two tithe Th power , W different brightness values that are , available to us on a channel by channel , by channel basis here and'm cycling , through of course the red green and blue , channels that are available to us here , inside of throb image SO x W x , W that's how many potential colors we , have inside of this image that's why we , have available to us as many As's.8 , million colors now there arena'sixteen , point eight million pixels inside of , this image so we're by no means taking , advantage of every single one of those , colors we're in fact only probably , taking advantage of about one or two , million colors however we have that many , colors available to us if we want to , take advantage of them now that is , actually the lowest bit depth mode , that's available to us inside a , Photo shop so that's the fewest colors , that you can have available to you , inside of a full color image you can , actually take advantage of more if you , want to if you go up tithe image menu , and you choose the mode command you'll , see that you have eight bits per channel , as well as sixteen bits per channel and , W bits per channel so sixteen bits per , channel is going to , liver two to Thoth pow eras it turns , out'm not gonna go into why that is , bu tit's just little weird technical , thing you have to to the Th power or , W,W brightness levels dominance , levels available to you on a channel by , channel by channel basis meaning you , could have as many as several billion , colors inside of an image and W bits , per channel goes even farther than that , goes into this huge realm where you , actually have all these floating-point , computation sand a bunch of other things , it's overkill it's total overkill fora , standard photographic image but bits , per channel can be useful I'm gonna go , ahead and convert this image to a W bit , per channel image and notice we now see , RGB/ W up here Ina title bar , now that did't miraculously generate , colors inside of the image , it just gives us a lot more wiggle room , I'll tell you what I'm gonna do I'm , gonna do Little bit of a demonstration , here by going up to the image menu , choosing adjustments and then choosing , this command right here the levels , command and I'gonna go ahead and , squish the colors inside of this image , I'm gonna change the output levels , values to for black and then W for , white so I'basically saying anything , that used to be black make it a , dominance level of W now which is a , very very light color as you can see we , can barely see the image on screen at , all anymore and also go ahead and darken , white just a Titch and let's say the , reason I'm doing this is because I'm , working with a really old version of , Express or page maker or something , hideous like that , and I want this image to appear in the , background behind some text so I just , want this slight image with some text in , front of it alright so anyway I'm , squishing the histogram I'll go ahead , and click OK in order to accept that , modification so I just dramatically , reduce the number of colors inside the , image now let's say Changed my mind , it's you know whatever it's a year later , and I come to this image and I go oh my , gosh I killed the only good version of , this image I have this is what's left if , I were working in an bit per channel , image I'd be in bad shape in fact why , don'twee go ahead at this point and , convert this image to the 8 bit per , channel mode just so that we can see , what incredibly bad shape , would be in so now I'm working in an , 8-bit per channel image once again'll , go ahead and press ctr L or command , on a Mac in order to bring up the levels , dialog box and try to undo the damage , that I'vie done by changing this value , the input levels value to W and then , the white input levels value to SO , I'm basically undoing that damage I'm , gonna stretch this totally squished , histogram'll click OK in order to , apply that modification and now if you , zoo min on this image you're gonna see , all this hideous pasteurization going on , now you might not be able to see it in , the video very well because our video , gets down sampled a little bit but on , your screen you're gonna be able to see , it very easily you're gonna see what's , called pasteurization's contrasts , between one color and its neighbor and , you can especially see it in the , background where things are gonna look , really super noisy inside of this , background and all the way over here on , the far left side of the image'vie got , a couple of gradients going on you can , check them out as well and you'll see a , ton of pasteurization and harsh noise , going on inside of that region all right , but that'predictable right of course , it's gonna look terrible and if we were , to go back to the levels dialog box so , we can see this big histogram here you , can see how big the gaps are between the , colors inside of the image so we have , very few colors left all right so I'm , gonna cancel out of that let's go ahead , and back step couple of operations , here I'm gonna press ctr alt Scuttle alt , Z a couple of times in a row that would , be command option Z command option Z on , the Mac so we're back to the bad version , of the image but in the-bit per , channel mode as you can see up here , inside of the title bar now I'm gonna go , back tithe levels command once again , there's my squished histogram and I'm , gonna change that first value the black , value to and I'm gonna change the , white value to and I'm gonna hit the , okay button , and now there'still noise inside of , this image and there's Little bit of , banding in a background but it looks , considerably better and if I scroll over , to this location you can see that we , don't have nearly that kind of , pasteurization going on inside of the , woman's neck for example where it's the , most obvious and if I press ctr , l or command again to bring up that , levels dialog box you'll sea very , smooth histogram so that's the benefit , of working inside of the W-bit per , channel mode even if an image starts out , is an-bit per channel image you can go , into W-bit and apply your modifications , and basically get away with murder , mean you can really apply some harsh , modifications to the image and still be , able to go back in a non-destructive , fashion so that'SWAT's going on with , W-bit the reason I mention it is not , only because it applies to channels but , also because it applies to masks you can , still create masks inside the W-bi tor , W-bit per channel mode something you , Warren'table to do in the old days but , you can do now and that means that you , can a smoother sharper better masks if , you want to go that route you do also , increase the size of your image note , that and you limit the option sin terms , of saving the image if you're gonna be , working with the W-bit per channel , image you have to save iotas stiff , image or a PSD image instead of a JPEG , these are just things to know alright so , anyway there it is just yet another , option that'available to you in this , miraculous program Photoshop in the next , chapter we're gonna take our first look , at masking stay tuned , membership Linda.com unlocks this , entire 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