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Graph­ics edi­tor GIMP and of­fice suite Li­breOf­fice ex­plained

Mac Format - - CONTENTS - Alex Thomas

With sum­mer just around the cor­ner, there’s ev­ery chance you’ll have hun­dreds of pho­tos on your Mac that need edit­ing and tweak­ing at some point. But if iPhoto isn’t up to the daunt­ing job, give the ‘GNU Im­age Ma­nip­u­la­tion Pro­gram’ (or GIMP, for short) a try.

This free-to-down­load im­age-edit­ing soft­ware has many of the high-end fea­tures you would ex­pect to find in pro-level apps such as Pho­to­shop. These in­clude tools and el­e­ments such as paths, las­sos, al­pha chan­nels and lay­ers. How­ever, un­like the Adobe apps, which cost a pretty penny, GIMP is to­tally free to down­load from gimp.org. Plus, be­cause it’s an open-source pro­gram, GIMP is con­stantly be­ing up­dated with new fea­tures and plug-ins to help it keep pace with its high-end com­peti­tors – all free of charge!

Get­ting started

The work­ing en­vi­ron­ment in GIMP will be fa­mil­iar to any­one who has used an im­age edi­tor. There’s a collection of tools on the left-hand side, and pal­ettes (known as ‘di­alogs’ in GIMP) on the right, fea­tur­ing lay­ers, gra­di­ents and your

This free im­age edi­tor has many of the high-end fea­tures found in pro apps such as Pho­to­shop

doc­u­ment his­tory. You can find out more in our an­no­tated im­age at the top of the page op­po­site.

When start­ing up GIMP for the first time, you’re given the op­tion to choose one of two screen modes – mul­ti­win­dow or sin­gle win­dow. Multi-win­dow is the de­fault and en­ables the di­alogs to be moved around at will – ideal for users with more than one screen. Sin­gle win­dow mode cre­ates a rigid in­ter­face, with di­alogs in fixed po­si­tions, which is sim­i­lar to iPhoto or Pho­to­shop El­e­ments – per­fect for beginners.

On the sur­face, GIMP may seem fa­mil­iar, but there are some sig­nif­i­cant dif­fer­ences, so whether this is your first time with GIMP or if you just want a quick guide to some of the fea­tures,

we’re go­ing to run through five com­mon im­age-edit­ing tech­niques and how to achieve them.

Crop­ping your im­ages

Se­lect the Crop tool from the Tools pal­ette (it looks like a scalpel), and cre­ate your cho­sen crop by drag­ging and se­lect­ing. If you don’t get it right first time, don’t worry, you can tweak the se­lec­tion area us­ing the high­lighted square ar­eas in the cor­ners.

To keep the as­pect ra­tio con­stant (the re­la­tion­ship be­tween the height and the width of the im­age), hold down ß when mak­ing your se­lec­tion, or se­lect the Re­tain As­pect Ra­tio check­box in the Tool Op­tions pal­ette on the left­hand side. In here, you can also amend other vari­ables, such as the out­put size of the im­age you are cre­at­ing, as well as the res­o­lu­tion.

To straighten an im­age, just se­lect theRo­tate Layer tool from the Tool pal­ette, which brings up a grid to help you line up your pic­ture per­fectly, or you can en­ter ro­ta­tion val­ues as num­bers to get your hori­zon per­fect.

Colour bal­anc­ing

If you think iPhoto’s ‘En­hance’ func­tion is a bit limited, GIMP has a num­ber of pow­er­ful colour-edit­ing tools, which can be found in the Col­ors menu. The most ba­sic op­tion is Bright­ness and Con­trast, which en­ables you to make quick and easy tweaks to the light­ness and dark­ness of your im­age. But if that’s still too ba­sic, try Hue and Sat­u­ra­tion. This al­lows you to edit the colours in your im­age with more ac­cu­racy, as well as ad­just­ing the bright­ness of some or all of the colours in to re­move colour casts or fix sim­i­lar is­sues. You can also do

this us­ing Colour Bal­ance, which lets you ad­just colours in the high­lights, shad­ows or mid-tones re­spec­tively.

These three are still rel­a­tively ba­sic, so if you’re feel­ing more ad­ven­tur­ous there are also Lev­els and Curves. These will be fa­mil­iar if you have any ex­pe­ri­ence us­ing higher-end im­ageed­it­ing pro­grams, such as Pho­to­shop. They let you ad­just the tonal range of the im­age through the im­age’s his­togram (a vis­ual rep­re­sen­ta­tion of the colours within your im­age). You can ma­nip­u­late points on the curve or the points un­der­neath the Lev­els his­togram to get the per­fect im­age.

If you’re not com­fort­able mak­ing these kinds of man­ual changes, there are ‘Auto’ op­tions for all these tools, which per­form fixes to your im­ages at the click of a but­ton.

Mak­ing se­lec­tions

If you’re look­ing to ap­ply a colour change to a spe­cific part of the im­age rather than the whole thing, GIMP has a fan­tas­tic collection of se­lec­tion tools. As well as the stan­dard rec­tan­gu­lar and el­lip­ti­cal Mar­quee tools, there’s also a free­hand Lasso tool, which en­ables you to se­lect parts of your im­ages by draw­ing around them with your cur­sor. With any se­lec­tion tool, once you’ve made your se­lec­tion, a dot­ted line ap­pears on the screen (known col­lo­qui­ally as ‘march­ing ants’), and you can then ap­ply ad­just­ments to just these parts of the im­age.

If you’re af­ter some more so­phis­ti­cated op­tions, you can use the In­tel­li­gent Scis­sors tool, which al­lows you to se­lect ar­eas of your im­age us­ing a smart lasso. Sim­ply draw points around the sub­ject you want to tweak and GIMP at­tempts to de­tect its edges, fill­ing in any gaps. If it doesn’t ap­pear to have found the edge cor­rectly, you can add more points or move ex­ist­ing points around un­til they are just right. Once drawn, sim­ply click in the mid­dle of the se­lec­tion and the ‘march­ing ants’ ap­pears, turn­ing it into a se­lec­tion.

Work­ing with lay­ers

Here’s the key thing that iPhoto does not of­fer. As im­age edit­ing gets more com­plex, it‘s worth be­gin­ning to work with lay­ers. Lay­ers al­low you to stack up parts of an im­age on top of each other and move them around with­out

af­fect­ing the area be­neath – it’s as if your im­age is a stack of pa­pers and you can move the sheets around in­de­pen­dently of each other.

To work with lay­ers in a non­de­struc­tive man­ner, use Layer Masks. See our walk­through start­ing be­low on the opp­po­site page for a quick guide.

Re­siz­ing and sav­ing

Once you’ve fin­ished edit­ing your im­ages, it’s time to de­cide how you want to save them. GIMP sup­ports all ma­jor im­age files for­mats, in­clud­ing JPEG, PNG and TIFF, as well as it’s own na­tive for­mat, XCF. Be aware, though, that GIMP only saves your ed­itable, work­ing documents in XCF mode, so to pro­duce a JPEG ver­sion of your im­age, you have to use the Ex­port com­mand, rather than Save As.

To re­size im­ages for web use or to make low-res thumb­nails, go to Im­age > Scale Im­age. Here you can see the im­age’s di­men­sions and edit them ac­cord­ingly. By de­fault, they ap­pear mea­sured in pix­els (px), but this can be changed us­ing the drop-down menu if you pre­fer. Here you can al­ter the size of the im­age in or­der to re­duce it for post­ing on­line. Any changes you make to the pixel di­men­sions al­ters the phys­i­cal size of the im­age and so re­duce the over­all size of the file, which makes it per­fect for up­load­ing. Just re­mem­ber to make sure the im­age is set at 72ppi, which is the stan­dard for dig­i­tal im­ages on the web.

For print im­ages, go to Im­age > Print Size and here you can ad­just your im­age for print­ing out. If you al­ter the width and size, re­mem­ber to re­tain the pixel di­men­sions, to en­sure you get the high­est im­age qual­ity you can for print­ing out.

Once fin­ished, you can save your im­age in a va­ri­ety of for­mats. For on­line im­ages, choose JPEGs and ap­ply com­pres­sion to re­duce the file size even fur­ther – but be care­ful with ap­ply­ing it heav­ily, or the im­age be­comes blocky and ‘arte­facted’. For files with in­di­vid­ual lay­ers you wish to re­tain, save them as TIFFs – but be aware they’ll be very large file sizes.

Multi-win­dow mode lets you po­si­tion di­a­log boxes wher­ever you’d like them.

When ro­tat­ing an im­age in GIMP, a grid will ap­pear to help you to line up your ver­ti­cals and hor­i­zon­tals.

Ad­just your im­ages’ colour bal­ance sim­ply and eas­ily us­ing Curves.

Edit the size of your im­ages for web or print and ex­port them as JPEGs, PNGs or TIFFs.

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