Introducing the Gimp

The interestingly named Gimp - which stands for the GNU Image Manipulation Program - is one of the heavyweights of the open-source software movement. Open-source software is free for anyone to download and use, and the Gimp is no exception. In many respects, it's the match of the commercial packages you'll find on p102 onwards, and it has many of the same features.

Some people absolutely swear by the Gimp and wouldn't use anything else. It's been in development for more than a decade, and many of its features - for instance, its undo facility - were way ahead of their time when originally incorporated into earlier versions.

The drawback, however, is that its interface is a little idiosyncratic and not terribly easy to get to grips with. But since it's free, you may as well give it a whirl before you consider splashing out on a paid-for package.

installing The first hurdle is installation, which isn't quite a one-click affair. Although Mac or Linux users can download the Gimp from www.gimp.org, Windows users need to download a different installation package. Head to http://gimp-win.sourceforge.net/stable.html instead and download from there. The good news is that the installation routine has been massively refined in recent years, and where installing the Gimp was once fairly complicated, it's now pretty straightforward.

Once installed, when you first start up the Gimp it will feel odd: it doesn't particularly look or behave like a normal Windows application. You're presented with a free-floating toolbar palette and a floating window - known as a "dialogue" in Gimp terms (which is at odds with the usual definition in the world of Windows). There isn't the big, blank image window you'd expect and which you get from other image editors. But persevere: once you get used to the Gimp's unusual presentation and occasionally quirky menu behaviour, you'll quickly come to like the huge amount of power it has on tap.

opening an image If you clicked through and accepted the defaults during installation, you won't be able to just double-click on an image to open it, since the Gimp is so well behaved it doesn't reassign file-type associations. So, to open an image you should click on File and select Open. You'll find that even this seems a little alien and doesn't look at all like a standard Windows dialog. This strange presentation and non-standard look and feel betray the fact that the Gimp's origins weren't in the Windows world - it was originally written for Linux and has

The Gimp offers a full range of editing tools, exactly as you'd expect from a package to rival Photoshop. There's very little missing.

The Gimp fully supports layers for advanced editing tasks.

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The Gimp fully supports layers for advanced editing tasks.

been ported across. To some extent that's the price you have to pay for a powerful image editor that's free. Persevere for a while, though, and you'll get used to it.

It has its benefits, too; you'll notice in the Open Image dialog that the standard Windows XP locations such as My Documents and My Pictures that you'd normally find in the tree on the left aren't there, but a useful feature is the Add button beneath the left-hand device list. This lets you bookmark any folder, including My Pictures, so it will always appear in the left-hand pane from then on. Notice, also, that there are left-arid right-hand scrolling arrow buttons; folders you're navigating to appear at the top and you can go directly to them using these buttons.

basic operation Now try opening a photo by using the File | Open Image dialog. By default, the Gimp scales the picture to fit neatly into the window. The quickest way to zoom in and out is by holding down the Ctrl key and using your mouse's scroll wheel. You can also right-click on the image and select View | Zoom, or select the Zoom tool (the magnifying-glass icon) from the main toolbar palette. You can then either drag a zoom box, left-dick to zoom in a step, or hold down the Ctrl key and left-dick to zoom out a step.

Now that you actually have an image open, you'll see a range of menu options in the top menu bar of the image window; this is where things become more familiar to users of standard Windows applications. One of the advantages of getting to grips with the Gimp before you move on to more expensive photo-editing software is that, if you do upgrade to the likes of Photoshop, you'll find that the Gimp's menu options, toolbars and features are very similar.

layers The Gimp is a fully layer-aware app. If you haven't encountered the concept of layers before, they're a very powerful way of doing advanced image manipulation. For instance, if you load two photos together and assign them to different layers in the same overall image, you can then easily adjust the opacity of the top-most image so the bottom image shows through. This mimics the old technique from film photography of double-exposure, where two pictures were taken on the same piece of film, leading to a ghostly merging of the two. As well as altering opacity, you can also blend layers together using any of 20 different pixel-evaluation schemes; the advantage of that may not be immediately obvious, but turn to p134 and you'll see how blend modes can be used, for instance, to help produce interesting cross-processed photos.

There are dozens of other uses for layers, too, which you'll discover as your experience in photo editing progresses. Layered images can consist of as many layers as you have the memory and hard disk space for, although remember that every layer you add to an image doubles the memory it requires - if you really start going to town with your layers, you may well need an extra helping of RAM in your system (see p93). The Gimp's layer features are flexible - by default, the Layers tab is open in the standard layout (see screenshot above). You can click and drag layers to change their stacking order, or drag a layer across to another open image to copy it into that image's layer stack.

history To the right of the Layers tab, you'll see a tab with a yellow arrow. Click this and you'll see Undo History. Every time you make a change to an image, the history is updated, with a small thumbnail image of the result of the change. To go back to a previous point in time and undo a change you don't want, all you have to do is click on ►

DIGITAL PHOTO SOFTWARE

one of the thumbnails and the image immediately reverts to how it looked after that step. Going forward again to where you just were is a simple matter of clicking back on the thumbnail at the bottom of the list.

modules One of the key features of the Gimp is its plug-ins - software modules that extend its features and functions. In fact, almost all the features in the basic installation are provided by plug-ins written by various third parties in the spirit of open-source software. You're not restricted to the plug-ins that come with the Gimp by default, though - there are dozens more available for free from http://registry.gimp. org. If you have a photo open, you can get a glimpse of the power and range of operations on offer by selecting Filters from the image's menu. They range from simple but essential enhancements, such as Sharpen, to obscure specialist operations such as Max RGB. This is where the Gimp begins to look like a viable free alternative to Photoshop - practically every option available to a Photoshop user is also available in the Gimp. But filter modules can be far more than simple effects.Try, for instance, going to the Filters menu and selecting Render | Gfig. This obscure module is in fact almost a complete application by itself, allowing you to do vector drawing (drawing geometric shapes and lines). Selecting Gfig produces the Gfig interface, allowing you to draw a range of vector objects on to your image. This isanother example of the power of layers, since the objects are incorporated into a new layer of their own, and don't affect the pixels of layers beneath, allowing you to quickly return to your original image.

scripting One menu option the Gimp offers that you won't see in any other photo application is the Script-Fu entry. This range of tools are, as the name suggests, automated scripts, again written by third parties and automatically able to do any number of clever things to your photos that would normally take some time to do manually. For instance, with a photo open, try opening the Filters menu list and selecting Decor | Old Photo. This produces a small options window that lets you select a variety of operations and filters, all of which affect the image in certain ways to give a photo an aged feel. Run the script on one of your photos (click Work on a Copy first) and you'll see it working sequentially through a number of operations, which it invokes one by one to get the end effect. All you have to do is sit back and watch. The number of operations available is extensive - fancy a coffee stain on your photo to make it look as if it's been lying around for a while? Easy, just select Coffee Stain and off it will go.

saving your work It goes without saying that when you're labouring over a photo to enhance it, you should regularly save your work (but always remember to make a backup of the original, so that no matter what happensyou always have the unretouched "digital negative"). You can't simply save an image that's had layers added as a standard JPEG photo, as the JPEG format doesn't support it. Instead, the Gimp has its own file format for saving work in progress. These files have a XCF file extension, and save everything about your current editing session, right down to the positions of your windows. The only thing that isn't saved is the undo windows, so you can't save an image, come back to it later and return to a previous point. Once you've finished retouching your picture, you can then save it as a final JPEG by "flattening"the layers into one and choosing the JPEG format when you save. As with the Open dialog, the Gimp's Save dialog is initially cryptic to anyone used to Windows XP's "Save As" box. You need to click on the Select File Type label to make it display the file-type options.

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Even opening an image can initially be confusing when using the Gimp. A bit of practice will go a long way.

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Even opening an image can initially be confusing when using the Gimp. A bit of practice will go a long way.

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