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Sunday, February 28, 2010

Filetypes in Photoshop



I'm constantly receiving artwork from clients that do not understand art files, and I doubt this will ever change. What an "art file" is, is either a Raster Image or a Vector Image, theoretically one of good enough quality to be produced. One of Photoshop's many strengths is the fact it can often handle ridiculous and exotic art files. Although many of these are the same, or at least incredibly similar, let's go over some of the more common ones and talk about what advantages they have, and briefly discuss what makes an appropriate art file.



PSD: This is the big one, y'all. PSD is the Photoshop file, proprietary to Adobe Software. Thankfully, it's not so proprietary that it's not become a standard for numerous graphics platforms. GIMP, which will run on nearly every platform of mainstream modern computing (Windows, Mac OS, and Linux) will open a PSD file without flinching. It will also keep track of the number one feature of a PSD file, Layers. Photoshop lives and dies by layers, as they allow you to build on top of your existing image without losing the information from the original. I have worked in non-layered Graphics programs. I promise you I will never return.

PSD files are Raster Graphics, meaning they're made of Pixels. However, since you have the ability to use layers, Photoshop files are considered "live" artwork, although it's quite possible to kill them by flattening the artwork inside Photoshop and saving them as PSD files.

Another potential problem with Photoshop is that newer versions may save in a file format that the older versions cannot work with. So if you're working with a graphics agency or print broker with an older copy of Photoshop, you'll need to learn to convert it to legacy formats.

It's also important to note that there's no magical benefit to PSD files. If you only have a JPG of your art, and your art person asks for a PSD, you can't fool her by converting the existing artwork to PSD. They could just as easily do that themselves, and it would be just as useless for everybody involved.



AI
: Another important format, AI is the native illustrator file. Less ubiquitous than Photoshop, AI files aren't the norm except for graphics-oriented people. (Illustrator is, if you can believe it, perhaps less user friendly than Photoshop. It is, however, just as powerful for slightly different applications.) AI files are Vector Images, as opposed to Raster Images. Vectors are infinitely scalable, which means you can make a vector image at 2 inches square and print it on a billboard with no loss of quality. They're also incredibly small files since when you create shapes in illustrator, you're only creating the bare minimum information to recreate the artwork you're producing. (I could be more specific and say something dense like "Illustrator is reproducing your artwork dynamically, based on instructions you create with points, lines, gradients, and shapes," but it's out of scope for this article and will be covered at a later date.)

AI files can be imported into Photoshop easily, except that Photoshop Rasterizes them, or converts them into a Pixels. Once Vectors are rasterized, they can't be edited as Vectors without returning to the original file. Sounds complicated, doesn't it? I can demystify it later, just understand you can only sort-of transfer files back and forth from Illustrator and Photoshop.

Illustrator also handles fonts differently from Photoshop. If you move a PSD to a different computer and there's a font you used that the new machine doesn't have, your design will stay intact. Illustrator requires those fonts to dynamically rebuild your artwork upon opening. So if you move the file to a new machine, you're likely to run into trouble, and your design will change. However if you remember to select all of your fonts and "Outline" your fonts (Ctrl + Shift + O on Windows, Cmd + Shift + O on Mac) your fonts will no longer be editable and viewable on every computer with Illustrator or Photoshop.

Inkscape is a decent alternative to Illustrator, and a free open source download. If you're having trouble opening this filetype, Inkscape may help you.



PDF: Another Adobe format, there are dozens of PDF readers in the world, including the excellent program Preview for Mac OS X, and Foxit Reader for Windows. Adobe Acrobat is a weaker option for reading PDF files as it's bloated, slow, and the free version has important features locked out. Preview comes with Mac OS X, and Foxit Reader is a free download.

PDF files can be either Vector or Raster files. PDF is also a native Illustrator file, so you can save your high-end illustrator artwork as a PDF without losing any of your ability to open and edit your art. Photoshop and Illustrator will open either type without fail, although the Vector Type will open best in Illustrator, and you'll have more Raster editing options in Photoshop.

PDF is a great file format for printers because there's little to no problem with fonts defaulting and software to open, view, and print PDFs are readily available. Many printers, including FedEx Office, seem to prefer PDFs over more common filetypes like JPGs.



JPG:Best to get this one out of the way. JPGs are popular because they offer a smaller file size than other Raster files. They do not have the capability of layers, and worst of all, they are Lossy, meaning they lose quality when saved. They do this because they have a type of compression similar to the algorithmic compression of Zip archives or MP3 files, in that they find redundancies and throw away bits of quality in the image in order to keep file sizes down. This loss of quality will affect your artwork and cause noticable graininess or blurriness in your final product.

JPGs do have upsides. The small size has made them omnipresent on the internet, and every browser with graphic cabability will read them. They are very WYSIWYG (What You See Is What You Get). This means if you send somebody a JPG, you can be almost certain that there won't be any surprises with changed fonts or problems with legacy versions of Photoshop. JPG is a mature file format and you can be pretty sure even somebody with a 10 year old computer can open a JPG without trouble.



GIF: Compuserve GIF is an Indexed color-style file. This means that files saved as GIF have a palette of 256 pre-chosen colors and all pixels are limited to those colors. GIFs have some fancy, flashy features, like Animations and Transparency. But these are largely Web 1.0 era features--particularly Animation. There's not a lot of value to animated GIFs when you're printing T-Shirts or Business cards.

GIFs have relatively small file size, but don't have JPG style compression and loss of quality. The trade off is that they have their own loss of quality when the color palette is squeezed from 16.7 million colors into 256. Simply make sure you're happy with the look of your file before you send it off to be printed.



PNG: One of the lesser used files for printing, PNG was created to replace GIF files. It is an open standard and most modern web browsers should read it without trouble. It is lossless, and supports RGB and Index color modes. Most people do not save art files in PNG simply because it's not as accepted as other filetypes like JPG or GIF.

To this day, I have never been sent a PNG as artwork from a client. I may actually swoon from excitement when I am!


TIFF: These are a bit of an oddball of the bunch. TIFFs are large, lossless Raster Files that for some peculiar reason can be saved with Layers. I don't recommend saving layered files as TIFF, because it handles them clunkily, and your layered TIFF is likely to be extremely huge in comparison to a layered PSD file. Perfectly acceptable for a flattened file, but inferior as a layered file.



EPS: Another Adobe file format, EPS can either be live Vector or Raster images. Illustrator and Photoshop will read and write EPS. They are small and self-contained, and good documents for print. They are less common today, and PDF is likely a better option over EPS. Some printers, however, may prefer this filetype over others, so it is helpful to be aware of it.


Programs That DO NOT Make Artwork



Microsoft Word, Microsoft Publisher and Microsoft Powerpoint confuse most users into thinking they are making artwork. In reality, these are probably the worst things any user can create art for print in. Many print shops do not have versions of Powerpoint or Publisher, and none of these three create artwork in either a Vector or Raster style suitable for any sort of professional output.

I've seen clients send art over embedded in Word documents as clipart. This simply adds steps for resourceful artists to have to go through in order to print your artwork and adds no value to your work. You should use Microsoft Word when the important part of your document is the WORDS themselves, and not the layout, colors or graphics.

Publisher I have not ever used. I imagine it's a program similar to old Clipart style design programs like InstantArtist and PrintArtist from my youth. The proprietary publisher format of PUB is not useful to anyone without Microsoft Publisher. We have had to turn away more than one Client who had designed his art in Publisher and did not have the wherewithal to export it to a more useful type of artwork.

Microsoft Powerpoint has no application in the print world; it is simply a type of presentation software. I don't recommend using it for anything but presentations, and never for printing.

The final word: Apart from the Microsoft programs above, every filetype on this page should get you a decent result if your artwork is created at actual size, and at 300 DPI. If this confuses you, you can look at my article on Resolution to understand more about Dots Per Inch and creating a good file for print. It's all about getting yourself better results!


What's next? Learn about Resolution, or about Pixels.

All graphics for this entry created by me are available under Creative Commons Share Alike License. All Licensed graphics available through the CC and GNU licenses they fall under.


Questions? I can help.


I'd like to encourage all of you that are interested to ask me your Photoshop and imaging questions. I'm extremely knowledgeable, and I'm willing to give you a hand.

Email me at understanding.photoshop@gmail.com and I'll get to work on helping you, answering your concerns, frustrations, and issues with Photoshop, as well as questions regarding images and other Adobe software.

Explaining Resolution: How dense is your image?


Image by clunky_wedding. Via Flickr.

When you're talking about any sort of image, it is generally good to think of it as having a purpose--your final intention of the image. Are you editing pictures of your wedding to print yourself? Are you making graphics for your website? Are you creating art for a shirt graphic? While we know Photoshop files are made of pixels, something often overlooked by Photoshop beginners is how many pixels the image has. One thing that will help you get a better final product is understanding a property of image files called Resolution, and tailoring it to your image's purpose.

Resolution is something I often have trouble explaining to clients. Just because an image looks about five or six inches on your screen doesn't mean it's going to look good when you fill an 8.5 x 11 inch piece of photo paper with it. The reason is likely because your file is low resolution.

It can help to think of old videogames when you think of resolution. Remember how blocky Mario used to be? That's because the NES was so limited in resolution that you could easily see the pixels. The NES had Low Resolution while newer video games are High Resolution, or High Definition, to use the television term. Pixels on televisions are no different than pixels on monitors, and not that different than dots printed on a page or T-Shirt.


This image is 72 DPI, and suitable for use on the web.
Image by Muhammmad Mahdi Karim. Via Wikipedia.

Resolution is best defined as Pixel Density. Basically, pixels (dots) can be any size we want them to be. If we make them smaller and put more of them in the same space, we get a smoother looking image. The way we track Pixel Density is with a unit called DPI, or Dots Per Inch. The smaller the dots, the more of them fit in a square inch, the better your image looks. It's that simple.

Low Resolution graphics are only good for your website and for looking at on the screen. Printing them out at actual size will give you visibly jagged images, or jaggies. Yes, that is a technical term. If you've ever downloaded a small image from a website and sent it to your printer, you'll see the results very clearly.

High Resolution images are suitable for various types of printing, including off your inkjet printer, on a poster, or on a T-Shirt. When you start with a good quality image, you have a better chance of getting a better result.


Click to load the image fully, and you'll get a better idea of how better resolution helps.


My clients often send me their artwork at small sizes of 72 DPI and lower. This looks okay on the screen, but when you look at the file at the size it's going to be produced at, suddenly the artwork seems very poor. See how smooth and invisible the pixels on the first moth look? The second is the same 1 inch square of picture, but zoomed in on 72 DPI. That image would be okay if it was very small, like image above. But zoom in on 72 DPI and you have a jagged mess.

Photoshop can try and "Enhance" images by stretching them up to a larger size. But your result will never look as good as one with a 300 DPI source. This is the problem with working with low resolution. When I get art intended for T-Shirts, I'm often given pieces that look like the second image, and when I ask for better artwork, clients try and trick me and give me the "enhanced" version on the right. Just remember, Photoshop can't create information, it can only change what you give it. If you put bad information in, you'll get back a product of bad information. In this case, a bad quality image with smudgy edges. In professional art circles (as well as in other forms of using data, like programming) this principal is called Garbage In, Garbage Out (GIGO).


"Enhance it!" No, Chris Cooper, that's impossible.
From The Bourne Identity, used without permission;assumed fair use.


I often get irate when I see movies show a low quality image from a webcam or security camera, and the FBI director or whatever tells the computer jockey, "Enhance it!" Remember, what you put into an image is what you get out. If you start out with a smudgy face with no detail, if you "enhance," you'll get a blurry, smudgy face with no detail. It's impossible to add without an artist going in and making up details, all of which may be wrong. Artists can create information, but Photoshop cannot. The basic thing to learn here is unless computers learn to think and act creatively, you'll have to use high quality art to get good results. And despite what movies may tell us, we actually are quite a ways away from computers acting creatively.

The final word: If you're using a digital camera, use a high Megapixel setting and you will usually not have to think about resolution. But if you're making art in Photoshop, start with a resolution high enough for your final purpose. 300 DPI is a standard for much of the graphics industry. If you work at actual size (8" x 10" art for an 8" x 10" photo print) and start at 300 DPI, you'll find you consistently get a better product. Just remember, if you start with high resolution and shrink your image, you'll lose no quality. If you start with low resolution and blow up your image, or "enhance" it, you'll have tremendous quality loss.

What's next? Learn about about File Types, or about Pixels.

All graphics for this entry created by me are available under Creative Commons Share Alike License. All Licensed graphics available through the CC and GNU licenses they fall under.

Understanding Pixels: Location, Opacity, Color


Photoshop is a medium of Pixels, short for Picture Elements. Basically, when you fire up any version of Photoshop and open the pictures you want to edit, what you see and what the computer sees are not exactly the same thing. You see a picture of a Quarterback getting ready to snap a football; Photoshop sees thousands of dots lined up on a grid, each with individual properties.

Those dots are called Pixels. They make up one of the two kinds of computer images. This kind of image is called a Raster image, and Photoshop is called a Raster program because it deals largely with those images made from square dots. The other kind of image is a Vector image, and I'll talk about that another time.

A pixel is the smallest unit of information within a Photoshop. Look at this zoomed image of the Quarterback. You get an idea of what the overall image is, but rather you see only the individual elements that make it up. These square dots are distinct from each other--they are separate and do not affect the ones around it. When you go down to the level of the individual pixel, you can't reduce your art to any smaller element, at least for our purposes. (Images are made from the same bits and bytes other computer files are made of, and those are the true building blocks of all data, but that is way out of scope for this article.)

Each of those dots have similar properties. When you open a picture, Photoshop reads a Location, Opacity, and Color for each of the thousands of pixels and renders them into something our eyes and brains can understand.

Let's go over these properties of pixels. Location is easy enough to understand. Photoshop puts everything on a 2D grid with X and Y coordinates. You don't have to refresh your algebra to understand it uses a grid of squares to keep track of where you want your pixels to go so it can put them there every single time. Once it knows where, it has to look at what Color and what Opacity each particular pixel is. Let's start with Opacity.

Past versions of Photoshop were the first image programs to introduce Layers, and as a consequence, Transparancy and Opacity. If the Opacity for some of your pixels is less than 100%, it is partly Transparent, and images below it in your layers will be affected by the transparent colors.

All layers in your Photoshop file have this same information: Color of dots, Location of dots, and Opacity of dots. It's important to keep these qualities in mind when you're working on your pictures because you can end up with a mess very quickly if you're working with a lot of layers. Opacity affects the color you see, not the color Photoshop sees. When Transparent colors overlap, they mix, showing you different colors. But if you still have the layers with transparent colors, the original color value is still there.



Notice how the colors blend, but the colors in my Layers Palette stay the same? That's how Opacity works throughout all of Photoshop, whether in the Layers Palette or with the Brush tool, or with other tools. You may see purple when red and blue blend transparently, but Photoshop sees two layers with lessened Opacity. The difference is that the colors remain separate entities, and can be returned to their original Opaque state.

Now on a more challenging topic--Color.



When you talk about color in Photoshop, you have to understand the computer doesn't know what "color" is. What it does "understand" pretty well is numbers. So, Photoshop keeps track of all the colors it has with numbers in different systems of Color Modes. These modes are RGB (for Red-Green-Blue), CMYK (for Cyan-Magenta-Yellow-blacK), Lab color(Lightness-a channel-b channel), and HSB (Hue-Saturation-Brightness). The two easiest to understand are RGB and CMYK, and they are also the most commonly used. For 99.9% of you, RGB will be the only thing you'll ever use or will need to use. I use Photoshop between six and ten hours a day and I rarely need anything outside of RGB for most of my purposes. Each has its own application, which I'll cover in another article, much later. For now, let's focus on RGB.

RGB is Photoshop's default color mode. Your monitor communicates to you through RGB because the so-called "primary colors" of light are Red, Green, and Blue. When these colors mix, you get pure white light, in Photoshop as well as in nature.



In this graphic, "Normal" represents Photoshop's Default Opaque layer effect. The "Screen" layer effect represents what that same color looks like as if it was light being cast--the brighter the color, the more opaque it appears. Red, Green, and Blue combine here to create white in the center. Red and Green combine to create Yellow, Blue and Red create Magenta, Green and Blue create Cyan.

These colors are represented by numbers in the corresponding channels, from zero to 255, a range of 256 options. Black has an RGB value of 0,0,0. White has an RGB value of 255, 255, 255. Any true gray is created by equal amounts of RGB, say 100, 100, 100. Pure red is 255, 0, 0. Likewise, pure Green is 0,255,0, and Blue is 0,0,255. Keep in mind we may not think of "Pure" Red, Green, and Blue looking like what Photoshop considers pure Red, Green, and Blue. But these are its primary colors, and as pure as you can get.

There are, of course, all manner of colors that are outside of the scope of this very narrow range of colors Photoshop can represent. This range of color is called a Gamut, which you can think of as a sort of box that contains the colors you can use--sort of like a box of crayons. But your monitor and printer can only represent a very limited number of the infinite subtlety of colors available in nature. But for our purposes, we have a palette of about 16.7 million colors to work with, with the rest of infinite spectrum of colors resting where we call Out of Gamut.

The final word:You do not need to understand all the subtleties of the various color modes to begin to use them, but dissecting RGB this way can begin to make Photoshop less overwhelming, and that is ultimately my goal for you. These principals, by the way, also apply to other Raster programs, like MS Paint, The GIMP, or CorelDraw. Until engineers come up with a better model for rendering colors, this is the standard we'll continue to work within. The important information to remember is that Raster Images are made of pixels, and pixels have three basic kinds of information attributed to them (Location, Opacity, and Color). Photoshop's default Color Mode is RGB, which I explained, but you don't need to have a deep grasp of--just understand it's basically limited colors tracked by numbers.

What's next? Learn about Resolution, or about File Types.

All graphics for this entry created by me are available under Creative Commons Share Alike License. All Licensed graphics available through the CC and GNU licenses they fall under.

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