Image Editing for Beginners - Training Handout
Upcoming SlideShare
Loading in...5
×
 

Like this? Share it with your network

Share

Image Editing for Beginners - Training Handout

on

  • 672 views

Summarizes everything covered in my Image Editing for Beginners workshop. Includes overview of the different image file formats, how-to instructions for using Gimp (the GNU Image Manipulation ...

Summarizes everything covered in my Image Editing for Beginners workshop. Includes overview of the different image file formats, how-to instructions for using Gimp (the GNU Image Manipulation Protocol), and a teaser for Inkscape and vector graphics.

Statistics

Views

Total Views
672
Views on SlideShare
621
Embed Views
51

Actions

Likes
0
Downloads
29
Comments
0

2 Embeds 51

http://tmjbeary.com 49
http://tmjbeary.wordpress.com 2

Accessibility

Upload Details

Uploaded via as Microsoft Word

Usage Rights

CC Attribution-NonCommercial-ShareAlike LicenseCC Attribution-NonCommercial-ShareAlike LicenseCC Attribution-NonCommercial-ShareAlike License

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Image Editing for Beginners - Training Handout Document Transcript

  • 1. Image Editing forBeginnersImage Formats...............................................................................................................................2.BMP.............................................................................................................................................2.GIF...............................................................................................................................................2.JPG..............................................................................................................................................2.PNG.............................................................................................................................................2.TIFF...............................................................................................................................................3Suggested Usage.......................................................................................................................3Software and Techniques............................................................................................................4PowerPoint..................................................................................................................................4Gimp............................................................................................................................................4PrtScr............................................................................................................................................8Resolution.......................................................................................................................................9On Screen images.....................................................................................................................9Printed images...........................................................................................................................9Raster vs. Vector Images............................................................................................................10Inkscape....................................................................................................................................10Additional Resources..................................................................................................................11
  • 2. Image FormatsIf you are scavenging images from the internet, then you pretty much have to take what youcan get in terms of the file format. When creating images from scratch, however, it is importantto consider which file format is the most appropriate for your use. See the PowerPointpresentation from this class for illustrative examples of these file types..BMPThe Bitmap (BMP) is a Microsoft Windows proprietary format and was once one of the onlyimage formats in existence. These images are high color and high quality but they do not scalewell and the files are uncompressed, which results in very large file sizes. Additionally, becauseBMP is a Windows format it does not always work across platforms. Many of the newer imageformats listed below resolve these issues and BMP images are rarely used today, except maybeby pixel artists..GIFThe Graphics Interchange Format (GIF) was created in 1989 and was the first format to be usedon the web. GIFs are limited to an 8-bit palette of 256 colors and provides lossless compressionif kept within this color palette. (If you try to use more colors in a gif image, it will becompressed until only 256 colors are used. For example, instead of using 5 variations of blue,the image will be compressed to use only one.) This compression results in a small file size,which made the GIF popular in the early days of the web when bandwidth was limited. GIF cansupport transparency and is the only format that can support simple animations. It is still in usetoday online for simple images such as logos, icons, and clipart..JPGThe Joint Photographic Experts Group (JPEG or more commonly JPG) format is the mostpopular format for use on the web today and has been considered the standard since 1994. JPGsupports high color images but uses “lossy” compression, so some image quality is sacrificed indeference to a smaller file size. This drop in quality is not necessarily noticeable at first glance,but becomes apparent when you zoom in or scale up the image. The JPG format does notsupport transparency and the lossy compression can make text difficult to read. Overall this is avery popular and appropriate format for photographs and complex images..PNGThe Portable Network Graphic (PNG) was specifically designed for the web and approved as aweb standard in 1996. It supports full color with lossless compression. PNG is a superior formatto GIF; it has more advanced support for transparency, results in a smaller file size, andImage Editing for Beginners 2
  • 3. provides higher image quality. The only exception is the fact that PNG cannot supportanimation. The PNG format is excellent for logos, icons, and semi-transparent images. It is notideal for large, detailed photographs as the lossless compression can result in file sizes largerthan JPG..TIFFThe Tagged Image File Format (TIFF) was created for use in desktop publishing, and is popularin graphic design, publishing, and photography. The TIFF is a very flexible format; it supportsseveral types of compression, a range of color palettes, and results in rich, high quality images.The drawbacks to TIFF files are huge file sizes, which rapidly consumes disk space, slow loadtimes, and incompatibility with some platforms. TIFF files are the preferred format forpreparing high quality print media, but should not be used on the web.Suggested UsageIn general, if you are creating images with text, line art, logos, or transparency you should savethem in the PNG format. Photographs should be saved as JPG files, unless they require the useof transparency. If you are very serious about producing high quality print media you can useTIFF files, although for most purposes PNG and JPG files will print adequately.Image Editing for Beginners 3
  • 4. Software and TechniquesPowerPointAnything you could show during a presentation can also be saved as an image for use on a wikior in a printed document. You can choose the file format from the “Save as file type” drop-down in the “Save as” dialog. Any of the image formats described in the previous section areselectable from this drop-down. You then have the option tosave every slide in the presentation or just the one you arecurrently viewing. The height and width of the image willbe based on the page setup settings in PowerPoint, see thetable below for details.Page Setup Pixels (WxH) Print size (WxH) Resolution (ppi)On-screen Show (4:3) 960 x 720 10” x 7.5” 96On-screen Show (16:9) 960 x 540 10” x 5.6” 96Custom (20” x 15”) 1920 x 1440 20” x 15” 96The print size of the image is accurate to the slide size in PowerPoint, and since the resolution isheld to a constant 96 ppi, the screen size (pixels) scale to accommodate the ppi ratio. The imagecan be further edited using GIMP, so if you want a higher resolution image a good strategywould be to scale-up the PowerPoint using custom page setup, save the image, then increasethe resolution in GIMP (which will reduce the print size to something more reasonable).GimpThe GNU Image Manipulation Protocol (GIMP or Gimp) is a free, open-source, cross-platformprogram that has capabilities similar to Adobe Photoshop. This is a tool developed for expertusers, so there is a learning curve associated with it. Luckily, the fact that it is free and workswell across platforms means there is a large community of users who provide online tutorials,templates, and other resources. Simply search for “gimp tutorial” and your topic of interest andyou’ll find several sites with the information you need.Image Editing for Beginners 4
  • 5. The BasicsWhen you first open Gimp you will see three windows. On the far left is the Toolbox, which hasquick access to thevarious selection,drawing, and colortools that you will usemost often. In themiddle is the Stage,where the canvas andall of the full menuslive. On the far right isthe Layers window,which you will use lessfrequently. For a moredetailed description ofeach tool see the GimpReference Guides inthe class folder. If youaccidently close the Toolbox or Layers, you can get them back under the “Windows” menu onthe stage.In many cases there is more than one way to access a given tool, so use the method you findmost comfortable. For example, every option in the Toolbox is available from the menus on thestage, but it is typically faster to select what you want from the Toolbox than it is to searchthrough several menus.Turning a JPG into a transparent PNGAdding transparency to a clipart image that has a single-colorbackground and well-defined edges, like the one shown at left, is asimple task.1. Open the image in Gimp.2. In the Layers window, right-click on the Background layer andselect “Add Alpha Channel”.3. Select the magic wand from the Toolbox, and click anywhereon the white background of the canvas.4. Go to Edit > Clear, or press the “delete” key on your keyboard.5. You should now see a gray checkerboard behind the star, this indicates a transparent region.Image Editing for Beginners 5
  • 6. 6. Make sure you save your file as a .png, otherwise (because .jpg cannot supporttransparency) it will look like nothing has changed.Working with Layer MasksThe above method for adding transparency works well if the image background is a singlecolor. But what do you do if you want to remove a more complicated background, like from aphotograph?The original photo After editingThe magic wand will only select connected areas of the same color, so it won’t work in this case.You could use the eraser tool, but what if 10 minutes into editing you discover a mistake youmade at the very outset of your work? The only option would be to undo back to that point, orstart over. Layer masks allow you to remove a complex background, in a basically error-proofway.1. Open the image in Gimp.2. In the Layers window, right-click on the Background layer and select “Add AlphaChannel”.3. Right-click on the Background layer again and this time select “Add Layer Mask”. Anew window pops up, keep the default “White (full opacity)” and click “Add”.4. The Layers window now shows a white box next to the Background layer, this is thelayer mask. Click on the mask to make sure it is selectedbefore continuing. It will have a white border around it.5. Anything you color black on the layer mask will become transparent. It gives you a wayto “paint the background transparent” without altering the base image. If you accidentlymake something transparent that shouldn’t be, just change to white and you can make itopaque again.Image Editing for Beginners 6
  • 7. Select the brush tool from the Toolbox, and start painting on the canvas. If a black spotappears, it means you have the base image selected and you need to select the layermask.6. To edit large areas you can use the select and fill tools to speed up your work. To make asmoother edge going from the child to the transparent background it helps to switchfrom the hard brush to the fuzzy brush. With the brush tool selected, additional optionsappear in the bottom half of the Toolbox window. Click thecircle picture beside the “Brush:” label to see all of youroptions. There are several unique brushes, in addition to thehard and fuzzy circles, and from here you can also vary thesize of the brush. To adjust the size further, use the scaleslider.7. Once you are finished, save the file as a .png. PNG files do not preserve layers, so if youanticipate the need to adjust the layer mask, you should also save the image as .xcf. XCFis the native file format for Gimp and preserves all layers and settings in the image.Composing Images with Multiple LayersAnything you can do to a single layer you can do with multiple. Working with multiple layersallows you to compose complex images. You can add a new layer by right-clicking in the blankspace of the Layers window and selecting “Add New Layer”. The default is the same size as thecanvas and you can choose between white, transparency, and the currently selected color. UseFile > Open as Layers… to open another image as a layer within the currently open image.The layers stack with the first layer in the list on the top of the image and the last layer in the listat the bottom. Click and drag a layer to change its position in the list. Renaming layers canmake it easier to compose complex images. Double-click on the layer name to change it tosomething more appropriate or memorable.Filters, Dialogs, and Scripts, oh my!The capabilities of Gimp far exceed my ability to document them in this one trainingcompanion. As mentioned previously, the online community is an excellent resource fortutorials and documentation on the use of Gimp. I also encourage you to take some time andplay around with the different effects to see the results first-hand.See the class PowerPoint and exercises for several examples. The example images from the classpresentation are also available in the class folder.Image Editing for Beginners 7
  • 8. PrtScrWhile most screenshot tools provide the same basic features, I like the interface and some of theextra settings available from PrtScr. It can be downloaded from the PrtScr homepage(http://www.fiastarta.com/PrtScr/).With this tool you can take a screenshot ofmultiple monitors (PrtScn), the active window(Alt+PrtScn), a rectangular area (PrtScn >Ctrl+left mouse), or a free-select area (PrtScn >left mouse) chosen with the mouse. From thereyou can give the image a title and save itdirectly to the desktop with that filename, orsave it to any desired location. You can copythe screenshot to the clipboard, attach it to anemail in Outlook, or open it directly in Paint forsimple editing.Besides these basic features, you can annotate the screenshot (PrtScn > right-click to draw)before you take it, and use the built in magnifier (Ctrl+PrtScn). This will zoom in to showindividual pixels on the screen, identifying the location and hex color code of each.To speed up workflows you can set an alternate hotkey, instead of PrtScn, and you can set adefault behavior: open dialog (shown above), save to desktop, open in Paint, copy to clipboard.Image Editing for Beginners 8
  • 9. ResolutionResolution describes the pixel density of an image, or the number of pixels displayed per inch(ppi). This ratio determines the image quality of anything that will be printed. Resolution is aconfusing topic because the term has been used inappropriately to describe the screen size ofcomputer monitors. When you say that your monitor has a screen resolution of 1680 x 1050you’re describing the number of pixels (1,765,000), not the pixel density.On Screen imagesMost monitors today range from 67 to 130 ppi, although many better-than-print displays havebeen developed. The recommendation for images that will be used online or in on-screen onlymedia is to use 72 ppi. Higher resolution (ppi) images could be used without ill effect, but dueto the inability of monitors to accurately display these higher quality graphics, it can result inunnecessarily large file sizes.When preparing images for the web, keep to a resolution of 72 ppi and scale the number ofpixels WxH to control the size that the image will be displayed in a browser window. Changeimage size or resolution in Gimp by selecting the Image menu > Scale Image.Printed imagesPrinters are able to achieve a higher resolution (ppi) than computer monitors, so therecommendation is to use 300 ppi for images that will be printed on paper. The human eyecannot easily distinguish differences in resolution above 300 ppi, so higher resolution imagesare just a waste of disk space. Adjust the print size (in inches) for an accurate idea of how largethe image will be when printed; in Gimp, select the Image menu > Print Size.For a concrete example, look at the parrot images below from the presentation examples.Image Screen size (px) Print size (in)Resolution-print-72ppi.jpg 461 x 288 6.4” x 4”Resolution-print-300ppi.jpg 1920 x 1200 6.4” x 4”Resolution-screen-72ppi.jpg 600 x 375 8.3” x 5.2”Resolution-screen-300ppi.jpg 600 x 375 2” x 1.25”Image Editing for Beginners 9
  • 10. Raster vs. Vector ImagesAll of the image file formats described in the first section of thistraining companion are examples of raster graphics. Rasterimages use a dot matrix data structure representing a grid ofpixels. Because the structure is defined as a grid of pixels, thereis a limit to how far you can scale a raster image before there is aloss of apparent quality. When scaled up the image will quicklybecome “pixelated” or blurry.Vector graphics, instead of being defined by a grid of pixels, aredefined by mathematical expressions for each path (line). Thisallows vector graphics to be essentially infinitely scalableimages. Vector images are limited to primitive shapes and texthowever, so they are not appropriate for all use cases. Onefamiliar example of a vector graphic is a PowerPoint autoshape, which can be infinitely scaledwithin PowerPoint without becoming blurry.InkscapeGimp was designed for the editing of raster graphics, but Inkscape was designed explicitly forediting vector graphics and provides a much better user interface to that end. Like Gimp,Inkscape is a free, open source, cross-platform software package that has a lot of communitysupport online. It is designed for expert users and skills gained from using Gimp to notnecessarily translate when working in Inkscape. Working with vector graphics is outside thescope of this class, but I wanted to mention it for those who wish to learn more on their own.Go to the Inkscape homepage (http://inkscape.org/) to download the software and find outmore.Image Editing for Beginners 10
  • 11. Additional ResourcesRemember to look through the other materials found in this folder: the PowerPoint from theclass, the exercises, and the folders of example images. Additionally, there are two Gimpreference guides that I discovered online and copied here so they would be easily available.Image formatshttp://www.1stwebdesigner.com/design/different-image-formats/http://www.graphicrating.com/2009/05/01/gif-jpg-and-png-file-formats-pros-and-cons/Gimp referencesGimp homepage - http://www.gimp.org/Gold-plated effect - http://boitblog.blogspot.com/2007/04/gold-plated-effect.htmlOriginal drawing - http://www.gimp.org/tutorials/Draw_A_Paint_Brush/Collage - http://puteraaladin.blogspot.com/2009/03/gimp-tutorial-creating-dark-surreal.htmlTypography - http://gimp-tutorials.net/gimp-text-effect-tutorial/PrtScrPrtScr homepage - http://www.fiastarta.com/PrtScr/ResolutionPPI recommendations - http://www.charlotteswebstudios.com/article.php?ttd=2&ark=21Image resolution - http://en.wikipedia.org/wiki/Image_resolutionComputer monitor resolution - http://en.wikipedia.org/wiki/Display_resolutionPixel density (ppi) - http://en.wikipedia.org/wiki/Pixel_densityRaster vs. Vector ImagesRaster graphics – http://en.wikipedia.org/wiki/Raster_graphicsVector graphics - http://en.wikipedia.org/wiki/Vector_graphicsInkscape - http://inkscape.org/Image Editing for Beginners 11