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Foundations of Adobe Photoshop CC

Lesson 12 of 36

Sizing Files In Photoshop

Dave Cross

Foundations of Adobe Photoshop CC

Dave Cross

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Lesson Info

12. Sizing Files In Photoshop

Lesson Info

Sizing Files In Photoshop

So now we're talking about re-sizing files. And there's a few things that we need to talk about in that regard. So whenever you open a photograph in Photoshop, it's gonna come in of course like we talked about this morning and then you're gonna look at in this case and say I'm at 66.7 percent so I'm pretty close to the full size of this particular image. But in order to get a better sense of what I can do with it, I have to find out a little bit more information about the size of this file. Now back in the days before digital cameras, we used to spend half our life in Photoshop talking about resolution. Like is it 300 PPI, or is it whatever or scanners and all that kind of stuff. And that discussion has gone from being vital to hardly ever talked about anymore. Because now to me it's much more important to talk about the size of the file. Because the resolution is sort of a side issue which is important when it comes time to printing to make sure you have enough but really even that is...

based on the overall file size. So in the early cameras that came out it was like you know a one megapixel camera so our overall file size was like four megabytes. There's not a lot you can do with four megabytes worth of information. That's pretty small, you could print like a four by six or something. As cameras got better, mega pixels got better that meant the file size was larger, more information that could be massaged into different areas. So one of the simplest ways to look at this is when you open a photograph, if you want to have a sense as to what you're able to do with this, then the simplest thing to do is to go to the image menu and a command called image size. And the image size is gonna tell you lots of very very useful information. At the very top it says image size and then a file size. Not pixels, not you know resolution, literally how much, how big is the file. So it's saying this is two point seven four megabytes. Which when Photoshop came out, would have been huge. That wouldn't probably even opened in Photoshop one. Now people are like oh, it's only two point seven megabytes, that's so small and it's like well yeah by today's standard it is. And then you can see dimensions of it in pixels and 1200 by 798 pixels and it says resolution 300. Now the only time that that resolution number really has any impact is if I was gonna print this. For anything else that's onscreen use, you can completely ignore that field, it means nothing. The pixel dimensions, width and height, that's the important thing. And therefore affects the overall image size. So as an example, if you have a photograph you've worked on you're like well I love this, I wanna send it out to a lab somewhere, you know some firm that you send digital files and they send you back prints, what's starting to happen 10 years ago a lot of those places would say make sure your image is 300 pixels per inch. But then they realized that that didn't tell people how big physically it needed to be, so often people would send a file that was physically too small at which still meant it wouldn't print properly. So then a lot of companies started doing the math and going send us a eight megabyte file, and people would say well what resolution? Doesn't matter, as long as it's eight megabytes I know that's enough information to print whatever the size is you're going for. So a lot of places now, if you go to a lab you'll see eight by 10 and now it has a number beside it like eight megabytes or some number. They no longer typically worry so much about is it 200 or 300 pixels per inch because it all comes down to the amount of pixels in that image which are determined by the size of the file. So as an example, let me switch this to inches. So this is from a printing standpoint, this is a pretty small file, because it's saying with the amount of image size you have, two point seven four megabytes the biggest you can make this is a four inch by two inch file. So one of the ways we can kinda see how this works is to use this almost like a calculator to kinda see so I'm gonna make a new document. Brand new and I'll just type in say 3,000 by 2, and click create, so it's just there's nothing in here right? Well technically there's never such a thing as nothing because in effect you can argue those pixels are all white. So it doesn't mean if I add color my file size will suddenly increase it will be exactly the same. But if I now go back to that image size command and change this to inches just for comparison purposes you can see, look at this file size, it's 17 megabytes now instead of two point seven which means I could go all the way up to an eight by 12. But I didn't change the resolution, they're both still it's because I have more pixel information due to the dimensions that it makes a difference. So needless to say a big part of this comes from your capture device, if you're taking a picture with an older camera phone when they first came out, it's gonna be a much smaller then that's gonna be your limiting factor. Or if you have some of today's cameras which are ridiculously big, you could print a billboard from that camera cause it's so much information. Almost in my opinion too much because the average person would never use all the resolution your camera gives. So when I'm talking about resolution in this sense, I mean file size, okay? So the only time I worry about file size, or sorry, resolution where the number of pixels per inch is if I'm printing this on my inkjet printer. Because I know through testing on my inkjet printer 240 pixels per inch is a good number. Someone years ago planted in our head that 300 is the right resolution for printing. It's not, it's just at the time they wanted to say that as opposed to people thinking they could send any file at all. But most people who have done any kind of testing finds that if anywhere between 200 and 300 is gonna give exactly the same result to the naked eye, there's gonna be no difference. However, a 300 pixel per inch file also means therefore the image size has to be bigger which means you're sending more information to your printer. It's gonna take longer for a no gain. So generally people do a lot of printing on their own device, kind of find their happy place of this number works well, so for me 240 is my target number. If I open an existing file, and say I need it to be a little different so let me show you how this works. This is where the kind of calculator part comes in. If you uncheck this little box that says resample, see how that little chain symbol linked all three? This is how I can massage the numbers see what can I get away with here? So if I've decided that the very minimum quality of resolution I could use on my inkjet printer is if I type that in, it says well now you can go as big as a 15 by 10. If I've decided that no I definitely need 300, then that tells me the biggest I can make is a 10 by six. So when people say things like is this photograph good enough to print at a big size? My first question is let's open the image size dialog box and see, cause I can't tell just by looking at it I mean I can look and see the number at the top says you're at an enlargement of 66 percent, so but that doesn't really tell me so let's look at the other photograph to compare. Remember it was a smaller size to begin with right. So if I go to image size and try this whole thing. It's saying well I guess if I were to drop it to I could go a little bigger but it's still five by three. It's not eight by 10, if I say well what happens if I make it 10 inches, we can do it but now the resolution's gonna be 120, that's really low for printing. Which is like a big warning symbol saying do you really want to do that. You could print this, there's nothing to say you couldn't but it would not look very good. So one of the ways we can tell is if you open a document that comes up from some source, someone just emails it to you, one of the first things I often do is open image size and see what am I working with here. And it always makes me slightly you know, really unhappy where I open it and at the top it says image size two megabytes, I'm like that's so small other than maybe for Facebook where it's gonna be this big on the screen. But any type of printing work that's a little different, that's why when people have their cameras and they shoot raw, that is the biggest image size in terms of megabytes. That's another reason when we talked before about you know raw versus jpeg, raw files are larger. Not a huge amount but enough that that's giving you more room to work with them. So one of the general rules of Photoshop that's very important is when it comes to resizing images, I hardly ever if ever want to resize up, meaning if I go to the image size and it's telling me that let's say if we take our image and I decide yeah, I need 300, it's telling me the biggest I can make this is four inches by two inches, if I say but I need it to be eight inches. That means Photoshop will artificially invent pixels that were never there and it will not look good. That's called interpolation and interpolation is an artificial way of enlarging an image. Photoshop does its best attempt but it's still never the same. So if you're creating something in Photoshop and you don't quite know yet the final result, it's gonna be for print, it's gonna be something given a choice, I would rather err on the side of it being too big than not big enough. If it means straining my resources a bit, I might think if there's even a remote possibility of it being printed as a 11 by 17 or a 13 by 19, I would start at that size. And then if they say oh no we only need it eight by 10, then I can shrink it down and not lose any quality. But if I start eight by 10, they say let's make it a poster, not good. Can you do it? Yes. Will it look good? No. And there's software out there that claims to be better than Photoshop, it's better but it's this much better. It's not like gonna make it the same. So this applies to any kind of sizing thing, and anytime you're transforming something, either the overall image or a portion of a photo in Photoshop. Scaling down is fine, scaling up generally not good. With a few exceptions, if you had a photograph of a cloudy sky that you're gonna ultimately use as a faded out background, then I'd be okay with enlarging it. Because I'm not worried about sharp detail of buildings and people, I just want this thing that people will say oh that looks, I think those are clouds in the back and that's fine. So there's always circumstances that will help but my concern is when people open a photograph and they start playing with numbers and hit save and now they just made their file go from 14 megabytes to two, and not really understand the implications of doing that. So if you're doing things for onscreen use, like you're preparing files that will be used in a video, you're posting on social media, that resolution number is not something you worry about, it's the dimensions. So for example someone says well for posting on Facebook use a longest measurement of 900 pixels, then the math will fill in itself, you don't have to worry about that. So in this case, I would just go back to pixels and say someone says it's 900. Now it's saying because I'm going down, it's now saying the image size is one and a half megabytes where it was two point seven four. If I were to click okay, which I will do for the purpose of demonstration, it's now a smaller file physically in the dimensions and file size however, do I want to make this a permanent change? If I do, if I hit save right now this is my new size, I can't go back to the 1200 anymore. So one of the recurring themes is if you do decide to make a smaller copy for some purpose like social media, then that suggests save a copy so this would be a version. So I have lots of photographs that say you know the name of the file and then another copy that says the name of the file dash 900 so I know that's the smaller social media one but I still have this nice big one that I can go back to if I need to, okay. When we talked before at length about non destructively image size is one of the most potentially destructive things that we don't think about. Cause if you size down for the purpose of output, that's its new size, and if you save it, no going back. So if you knew I need several different sizes of the same document, that's where I'd be making duplicate copies and saying hey this one will be full size, this one will be this size, whatever it is. Because this is one of those paths if you go down it, if you go image size yeah it looks great, click okay, save. Done. Actually that's not quite true. If you haven't closed it yet, you might have one undo, but if you've closed it, then done. So this is one of the few times in Photoshop where you'll, I'll find myself making several different versions for different sizing. Just so I make sure I have it. Now, I haven't talked about this too much so far but we do have these abilities in Photoshop for undo which means to go backwards. However it's limited in very much in terms of operations what you've done, so I can choose undo image size and go back a step. If you've done several steps there's a command called step backwards which allows you to in effect undo multiple steps to a degree but again, that's based on this thing called the history panel which is only active while the document's open. So if I did image size, hit save and closed the document I can't reopen and say step backwards, it's too late cause that's gone, it's gone. So just for comparison purposes, here's the other reason why we care about image size. We talked before about actual size and fit in window, let me go on this file to a hundred percent view and you can see that's a hundred percent. Alright so zoomed in a little bit, but not that much. So if I want to try to edit this in any way I'm a bit stuck cause as soon as I have to zoom in, we talked about then it gets a little pixelized, it's hard to see. So I have a second version of the same file, that is a bigger file if I go to image size, I'll just compare. This file is 34 megabytes as opposed to two point seven four you can see it's much bigger in terms of pixel dimensions or in inches. So now on this one if I go a hundred percent same command, but look at the difference. So much closer in because of the size of the file. So if you wanna do heavy duty editing and here's a perfect example, my only goal for this might be, the end result might be put it on Facebook. It's gonna be a whole lot easier to edit this one and then resize it than to work on one that's already the right size but I can't zoom in any further. So that's the kind of the game you have to play sometimes is remember that thing we talked about at the beginning. End up with this is a perfect example, I wanna end up with a nice looking photo for Instagram or Facebook or whatever it only needs to be this big. It's gonna be a whole lot easier to edit it at this size initially so I can zoom in and can see really closely. Just don't get caught up in the distraction of editing stuff that when you realize when you do scale it down, you might not see it, but at least for certain operations it's a little easier to start at this size. And if this was the case, let's pretend this was the case, I've done some editing now I wanna prepare this for Facebook, so the first thing I would do is save it as is, that's my master file. Cause I wanna make sure I don't lose my original size. Then I'd go to image size, and I'd say I do wanna resample cause I wanna make it smaller and I want the width to be 900, now it's gone from 34 megabytes to one and a half megabytes. Which I want, cause I want a smaller file size to put on my social media, and I click okay. This next step is crucially important. Not that next step, the next step. Save as, not save. If I hit save, this would be my new file size and I've painted myself into a corner of not being able to get out of it, so once I've finished editing it, and I've saved my original master psd file, then I do image size and save as and I would typically do something which hopefully makes sense to me like ice beach 900. As, I lost my mouse for a second, as a jpeg, click okay. Now I didn't talk about this before but I mention it in passing, jpeg by nature compresses, so you don't wanna compress too far, so I rarely if ever change this from the maximum of 12, cause I want to compress but not so much that I lose any quality. So unless someone tells you or you try to compress a file and they say oh it needs to be under a certain size, like one megabyte then you might go back and tweak it. But generally speaking the built in compression of jpeg for me is more than enough and I don't wanna lose any quality. That reminds me to mention that there's, I don't want to call it a myth, but it's a misunderstanding people often say things like we don't wanna edit the same jpeg and keep saving. Cause every time you save a jpeg, it loses quality. Sort of, if I were to save this as a jpeg, and then make a change and save it again, and save it again, and keep saving the same jpeg over the top of itself. After about three months, I'd probably notice a I'm exaggerating a little bit, but you need to do a lot at a really low quality to lose that much quality. There was, that was true years ago because jpeg used to always default to like a mid quality that would mean very quickly you'd lose quality. So for me, I never even look at this dialogue box when I save as a jpeg, I give it a name, I hit okay and okay without even looking at this dialogue box. Cause I always want it to be that size. So now I'll end up with, if we look over here in bridge, here's the original file that's the full size one, and I now have one that's a jpeg that I know based on the name is 900 pixels wide, that's the one I would upload to whatever Facebook, whatever I'm doing with it. Unless there's I can't even think of a reason why you would want to do this, I'm always gonna still want the full size one because someone on Facebook will say oh I love that can I get a print of that at eight by 10. Yes, now you can cause I know I have, if that's the only one I have, they'd be like no. Can I give you a print that's this big would you like that. Because that's, I mean math is what it is. I'm not good at math but I know that this is a restriction of pixel sizes, what you can and can't do. All the time I have people saying, so someone sent me this jpeg and they want me to print it as a poster. Right away I'm always like yeah okay. They sent it, they emailed you a jpeg, most email software cannot handle big files, I'm already saying, I'm already gonna guess what I'm looking at. And let's just open the image size command, how big is it? Four and a half megs, no. Or they'll get a poster which is very unattractive and they won't like it very much. Well can't you use software to enlarge it? No. I mean technically, yeah there's software that will enlarge it but it will never be the same. So if someone says I'll send you a jpeg, well okay but can you put it through dropbox or something where it's like the biggest possible file size, that'll help. Cause a lot of people don't, just don't get that something off Facebook or social media is already reduced down in size, you can't just put it back up again. It's gonna lose quality terribly. So keep that in your thought process all the time when you're thinking about planning ahead and I understand sometimes the challenge is well I don't know. I'm working on this image but I don't really know what it's for yet, I took these photos in Iceland and every single one as I started playing with them, I was doing everything at the biggest size I could. Because I might eventually say well I might just print that and put it on my wall. I hate to do all this work and then realize but it's at a size I did for Facebook and now I can't print it. So even though it takes up more room, physically on my hard drive, I'd rather have more information than not enough, cause there's nothing more frustrating then making something that looks beautiful and realizing it's this big. So you can share it on Facebook and say look isn't that lovely, can I get a print? No. I shouldn't say no yet, if you want a really ugly pixelized print, I'd be happy to give that to you. But nobody wants that, okay. So the good news is most cameras, even the ones we carry in our pocket, the quality, the file size is pretty darn big these days, so we're already starting at a pretty good place. Compared to the early days of cameras where it was like I just got a four megapixel camera, I can now print a five by seven, yeah. I mean that seems funny to say now, but that was the case. I was excited I had an extra inch now that I didn't have before, so with today's capture devices, this is less of a worry than it was before. But it's still something to consider. And throughout this whole discussion if nothing else sticks with you, just think, better to reduce than to enlarge. Enlarging, when you enlarge something, let's go back to image size, it even tells you this. In here it's saying there are all these methods that say well if I want to make it larger, there are these methods I can try but all of these are something again called interpolation which means I'll look at pixels and try and pick ones that makes sense. Nearest, nearby pixels things like that, but it'll never look as good. So let's say I decided I need this to be 3,000. You can already see in the preview, look at the edge there, it's terrible. If someone says yeah but I really need it to be 3,000 pixels, well those are your choices. I can give it to you at 3,000 but it will just not look good, or we just not let's do that. So that's the game we have to play but that's why I said that and I know it's the whole thing when I was changing it up or down, the resolution didn't change because it was the physical dimensions and therefore that image size which are really the key factors. The only time that resolution really comes in is when you're printing. But I've actually done things like postcards, for example with an online company, did all the work in Photoshop and they actually sent me a template that I downloaded. Or I took it from their website, that was like use this file, and it came up this big. So I just put everything in there and I knew it would work because it was their file. One look at the image I was like oh, it's six inches by four inches at 300 pixels, okay. But that was like less important than the fact that it was physically this big on my screen and I knew that's the right information because they created it for that purpose. Do you have like a cheat sheet with different ranges to play with for like say from poster to calendar to album to book, down to post Yeah I know what you're saying but I haven't personally because it, it's gonna depend a little bit on the method of output. For example, if I'm doing anything using a service, so it's not on my own printer, I know 240 pixels per inch, and then it's just a matter of dimensions. But if I'm doing anything else, like business card, postcard or something where I'm using some company the first thing I do is look on their site and see if they have something that, and most of them do. Will say has to be at least and they'll tell you this dimension and some will still say it has to be an eight by 10 at 300. Which is fair enough too, but some people go, kind of go ehh, what's that mean. So that would mean make a new document, put in eight by 10 inches and make sure the resolution is 300. So let's do this so you can see inches. 10 by eight, 300, create. How big is that? I don't know. Let's find out. 20 megabytes. So in that case, I followed someone's instructions and said make sure it's this, and then Photoshop does the math and says well this is now so I have to make sure that any images I'm bringing into this are of the right size. And this is something that we should talk about as well cause this throws people off, cause they're like well here I wanna put this photograph on this new thing I'm making, and they look kinda the same size, right. So I'll do it the old fashioned way first. Copy, paste, huh, it's really small. Well it is because the other one was this big and this one's this big, it just doesn't look like it on the screen. So if you look really closely, look at the number up at the top, come up here so you can see. This one's saying 66.7 percent, the one I was trying to copy, it was 16 percent. So in a way that's telling me the scales aren't the same so I shouldn't be surprised if I drag it over or copy it and it goes meep, because that's just the math. And if someone says well I'll just scale it up in the new document, no. I mean you could but same deal, you'll get really pixelized bad looking stuff. I got a question, Dave. Some like printing labs you can upload to, some you gotta send in to, when you're sending in a 20 megabyte file or a 30 or a 50. What service do you use or recommend? Do you have a favorite? I mean it's, I happen to use dropbox. Cause I just early on it worked for me but I'm finding more and more online services, they're getting better at what they can accept, so even a big file. Like I printed a canvas that was gosh, I wanna say five feet by four feet, it was big. And when I did the math in Photoshop, it was a big file. And I went to their website and said upload here and I went oh this should be fun. And it was like okay, right, and it actually generated a preview in like 20 seconds. I'm like that's pretty impressive cause my file in Photoshop was what I would call pretty huge, but it uploaded so I think more and I would say the bottom line is try and see. Most places have realizing that for bigger prints you're gonna need a bigger file so therefore they try to accommodate that. But if not then you're just transferring to someone else some file sharing thing like dropbox or some of the other ones would be good for that, too. So just to make sure I understood correctly, in the example you showed where you started by creating the file you needed was the right size. When you added the picture, it wouldn't change anything about the dimensions but it would change the file size. Well it's, what's really happening is when you're comparing, they're not the same relative size. So the first one, the destination file was the nice big one that was like you know whatever it was. 50 megabytes in size, this one was so small that even on the screen it looked the same as I dragged it over, it said well in relative to this size of document, this is the biggest I can actually make it. So it's taking, it's basically preserving whatever the pixel information, and because the pixel information in the smaller one, you can't just enlarge it. It's gonna look smaller on a relative base when you compare them. Yes but what I mean is if you go, if you open the size Yeah, that's yeah. That won't change because image size is the overall dimensions not file size. When you save it will get bigger because of more layered information but in terms of the image size amount that doesn't change. Okay. That's what I wanted to check. All these photographs that you showed they were color photographs, does the same apply to black and white? The same theory applies, the difference is by nature they'll be smaller because color requires more information to be that file size, so for example, this one that I did that was like eight by 10 cat 300, was 20 megabytes. If when I first made it I had said but I want it to be in grayscale, take this back. Eight, go to image size, see it's much smaller because it's still the same pixel dimension but doesn't require color information so that's gonna make it a smaller size. But of course that means if I were to copy in color pixels, they'd be converted to grayscale because it's the container document. Doesn't have the ability to display color.

Class Description

Join Dave Cross in this beginner friendly class starting at the very basics with Adobe® Photoshop® CC. You’ll learn how to begin navigating the software and what the best practices and work habits are to approach different projects.

Dave will cover:

  • Working non destructively on your files
  • How to resize, crop, and straighten images
  • Using layers with basic layer examples
  • Adding text, color, and painting to images
  • How to retouch and adjust images using selections and masks
  • Learn how to use the tools you need to create the image you want. Dave will demonstrate using sample workflows that take you through projects from start to finish.

Don't have Adobe Photoshop yet? Get it now so you can follow along with the course!

Software Used: Adobe Photoshop CC 2017

Class Materials

Bonus Materials

Adobe Stock Contributor

Bonus Materials with Purchase

Quick Notes Guide

Landscape Image for Practice Edit

Senior Portrait Missing Element for Practice Edit

Senior Portrait With Element for Practice Edit

Ratings and Reviews

Student Work

Related Classes



I really like Dave's methodical teaching style. Step by step works best for my learning processes. He also has a lovely voice to listen to during his classes, that is important if you have to listen to someone talk for any length of time. I also like the "dance" he does by explaining what he is going to do, then does it, and then comes back to explaining the choices he made and why. Very, very easy to follow him in his straight forward explanations. He increased my understanding of so many tools I use and so many I have never used. Wow! Photoshop with Dave took away a lot of "fear"! (Wish I had a "happy face" to place here!) I bought this class today because I don't think I can get along without it!

Jim Bellomo

I was so lucky to get to attend this class in person here in Seattle. I have been a fan of Dave's for years and own a number of his courses from Creative Live. When this class was announced I almost decided to skip it since it was listed as a "beginners" class but decided that it "might" be worth it. One of the reasons I wanted to take it was that I am self-taught. I had started with Photoshop 5 (not CS5 but 5) about 15 years ago (at least). I figured it I took this class I might learn a little something that would help me in my work. Well, two days later I have 18 pages of handwritten notes, a whole new way to work and it has already paid off in a huge way in my daily workflow. I bill out my hours at around $100 an hour as a graphic designer and marketing person. That means in the two days that I spent 10 hours a day taking the class and commuting to it, it cost me about $2000 in working time. But it didn't. I can guarantee that I am way ahead on this one. I l learned so much. The real world things I learned will pay off for a very long time. Within one day after the class I had already started changing my workflow to be more non-destructive and faster. Dave is an awesome teacher and I can't say enough good things about this class. Even if you think you know Photoshop, you don't. I teach it in my small world but I learned so much.


A writer and an old person (over 60), I rarely use neat exaggerations like "great" or "fantastic," and never say "awesome" in the currently fashionable manner. However, I would call this class both great and excellently planned. Cross is well-spoken and a consummate teacher with a rarely non-irritating voice. It is information packed, clearly presented, well-organized, and extremely helpful. I wish I could afford his others.