http://wiki.meetthegimp.org/ 2012-05-17T08:53:37+02:00 http://wiki.meetthegimp.org/ http://wiki.meetthegimp.org/lib/tpl/default/images/favicon.ico text/html 2011-04-02T15:18:32+02:00 http://wiki.meetthegimp.org/doku.php?id=animations&rev=1301750312&do=diff In difference to a video, animations are (usually) created frame-by-frame either manually or algorithmically, while videos originate from a moving picture source (aka a camera). This distinction is not totally rigid, but serves as a nice guideline. GIMP can be used to create and edit animations, either from scratch or pre-existing images. For more versatile tools and true video editing capabilities look at Blender3D and Cinelerra. The most common used animation file format on the web is GIF89a… text/html 2011-01-14T19:58:54+02:00 http://wiki.meetthegimp.org/doku.php?id=aperture&rev=1295031534&do=diff The aperture is a part of the lens, centrically reducing the light entering the camera. Its unit of measurement is dimensionless and called f. It is calculated via dividing the lens' focal length by the diameter of the aperture opening. The resulting value is written F[value] or f/[value]. It has two effects: Closing or opening the aperture changes the amount of light permitted to enter the camera and closing down the aperture blocks increasingly more defocussed rays of light, increasing the de… text/html 2011-08-04T11:15:50+02:00 http://wiki.meetthegimp.org/doku.php?id=batch_processing&rev=1312449350&do=diff During image editing and post-processing some steps are uniformly executed for a bunch of images and it therefore makes sense to automate them. Gimp offers a powerful scripting ability which can be (ab)used for this, but it's original intention and design goal is to automate and unify several image editing steps for a single image. Gimp is not alone, however and there are a number of accompanying programs around, specifically developed with the intention to mass process many images and reduce m… text/html 2011-12-26T00:29:39+02:00 http://wiki.meetthegimp.org/doku.php?id=bitdepth&rev=1324855779&do=diff Bit depth is the size of the datatype used to store the color information from one channel of a pixel. Normally this is uint8 which is 8bit and ranges from 0 to 255. Together with the most common color space RGBA and the three color channel being R(ed), G(reen) and B(lue) this gives a mximum of 16,777,216 (2563) different colors plus 256 different levels of opacity (A) for each and every pixel. So one pixel takes up 32bit all in all, usually stored in a uint32. text/html 2011-08-11T17:58:14+02:00 http://wiki.meetthegimp.org/doku.php?id=black_and_white&rev=1313078294&do=diff Black & White - also called monochrome or greyscale - means no color information in the image. Light has two (three with polarization) properties: Frequency (or temperature) which is the actual “color” and intensity which is the amount of light and called luminance, brightness or lightness (depending on the definition of considering a single frequency only or a wider spectrum). text/html 2011-08-26T17:50:27+02:00 http://wiki.meetthegimp.org/doku.php?id=change_the_image_size&rev=1314373827&do=diff There are two different methods for changing the image size, Scaling and Cropping. Scaling means recalculating the image's pixel to fill given dimensions. This way, an image can both be enlarged or reduced in size. Cropping is to “chop off” image parts and will therefore always reduce the image size. Unlike scaling it's a lossless process, the remaining image parts will not be affected. A third method exists, resizing the canvas (work area), but it doesn't change the image itself directly and… text/html 2011-11-02T20:29:51+02:00 http://wiki.meetthegimp.org/doku.php?id=color_light_contrast&rev=1320262191&do=diff Contrast Contrast is the difference in brightness between neighboring pixels or regions. Together with color difference this holds the actual image information. First is an example of an image without contrast — it is filled with only one color/shade of grey. Second image has the maximum possible contrast at the edge in its middle, because the difference between the black and white regions cannot be larger. text/html 2012-05-04T19:21:27+02:00 http://wiki.meetthegimp.org/doku.php?id=compiling_2.7_under_linux_debian_esp&rev=1336152087&do=diff This was covered in #154 for Version 2.7. There is a more general and permanent solution here 2.9 is a development version. There is a big chance that it will not compile or run properly. If so, try the next day or week. Compiling under UBUNTU is described for 2.7 at blog.bloke.com and it is working like a charm. How much has to be changed for 2.9 is currently unnown. text/html 2011-01-11T08:42:02+02:00 http://wiki.meetthegimp.org/doku.php?id=correct_tilted_images_and_slanted_buildings&rev=1294731722&do=diff The most common problem when photographing building or other tall structures from a low vantage point is “falling lines”. Due to the larger distance of the buildings roof than its bottom lengths become shrunken (intercept theorem). Aside from using an expensive tilt shift lens or shooting from a crane this can be corrected in Gimp with the perspective tool (Shift+P). Note that perspective correction is a highly degrading process and should only be done once. text/html 2010-11-19T15:23:59+02:00 http://wiki.meetthegimp.org/doku.php?id=critique_the_image_and_create_a_plan&rev=1290176639&do=diff Critique the image and create a Plan You start with an image from one of the “to edit” categories. First, take a careful look and figure out what needs to be done or changed. Sometimes, if you can't decide, put it back into the pipe and come back some days later. Getting some distance can help you see. text/html 2010-11-30T15:20:06+02:00 http://wiki.meetthegimp.org/doku.php?id=dodging_burning&rev=1291126806&do=diff These are used to selectively change the brightness/lightness of parts of an image. Dodging means avoiding the light, which - counter-intuitively - brightens the image. Burning is strong exposure to light, resulting in darkening the image. (The terms stem from the good old days of the darkroom - silver halogenid particles crystalize when exposed to light, causing the paper to darken.) text/html 2011-01-20T20:11:10+02:00 http://wiki.meetthegimp.org/doku.php?id=dynamic_range&rev=1295550670&do=diff Dynamic range is the ratio of the highest value (light intensity in the case of photography) to the lowest one. This is in every way a relative value, not only is there no true minimum value due to unavoidable vacuum fluctuations, there is also no imaginable maximum amount of brightness. The only way is to define both fixpoints depending on the circumstances at hand. text/html 2011-03-30T15:29:56+02:00 http://wiki.meetthegimp.org/doku.php?id=filters&rev=1301491796&do=diff Filters are special types of optical glass placed in the light beam by screwing them in at the front of your lens or inserted them into a slot in the back, which affect the incoming light. Tele- and wideangle converters don't fall into this category as they only change the crop (focal length) but not the contents of the photo, the same goes for tilt/shift addons. text/html 2011-04-01T00:17:46+02:00 http://wiki.meetthegimp.org/doku.php?id=flash&rev=1301609866&do=diff Aside from using a different exposure (shutter speed & sensitivity) there are two main methods to artificially lighten up a scene: Permanents lights, aka lamps, and stroboscopic lights, aka flash. (A third method was explained in episode 9) Both have their advantages and disadvantages. Lamps use a lot more energy and are therefore usually limited to studio use, but they illuminate the scene continuously giving you the chance to adjust and change the light before the shot. Flashguns are usually p… text/html 2011-06-25T23:37:30+02:00 http://wiki.meetthegimp.org/doku.php?id=getting_gimp&rev=1309037850&do=diff Get GIMP It's highly advisable to use a released, stable version of Gimp for real work. These are recognizable by the even number in the second place of their version number (e.g. 2.6.x, 2.8.x or 3.0.x) and can be installed easily with the package management of your distribution. The exact steps vary but in most cases there are graphical tools to do the job easily. text/html 2010-12-28T16:34:03+02:00 http://wiki.meetthegimp.org/doku.php?id=hdr&rev=1293550443&do=diff HDR images try to encompass the dynamic range of lightness in real, daily scenes. No normal camera, neither digital nor film, can record both the brightest highlights (e.g. direct sunlight) and the darkest shadows (e.g. a black object on the north side of a house) at the same time with the same lightness resolution. Either the highlights will be blown-out while preserving structure in the shadows or the shadows will just be pure black while getting details in the highlights. That isn't the only … text/html 2011-02-10T18:34:22+02:00 http://wiki.meetthegimp.org/doku.php?id=image_file_formats&rev=1297359262&do=diff Rolf covered the pros and cons of different storage formats in Episode 12. TIFF TIFF is a comparatively old universal container format, able to hold many different types of data of all kind, even several at the same time. Due to its versatility and complexity no program supports all possible or available TIFF files. To make file exchange, at least for images, reasonably possible a standardized subset called “Baseline TIFF” was created. TIFF is very flexible in the type of images it can hold. … text/html 2011-02-20T10:20:33+02:00 http://wiki.meetthegimp.org/doku.php?id=import_the_images&rev=1298193633&do=diff Importing means to get the images from a different device, via a variety of ways, into your collection. Note: If you start with an image downloaded from the show or send to you by mail, you can skip this step. While all of the management and most of the image manipulation programs named later on are able to import images from various sources, it's sometimes easier and/or faster to use dedicated programs for this purpose. text/html 2012-01-01T00:05:56+02:00 http://wiki.meetthegimp.org/doku.php?id=keyboard_shortcuts&rev=1325372756&do=diff A lot of GIMPs functions are bound to keys or key combinations, so they are easier and faster to activate without having to use the mouse. As explained further down, the bindings can be changed, so these are the default values: * Undo (Ctrl+Z) restores the image state before the last editing step (“moving down the stack”) * Redo (Ctrl+Y) is the oposite to undo and restores the state after the last editing step (“moving up the stack”) text/html 2011-01-03T20:39:17+02:00 http://wiki.meetthegimp.org/doku.php?id=layers&rev=1294083557&do=diff Layers are the primary building blocks of the image. They're one of the basic and most useful tools while editing. A layer can be imagined as a transparent sheet of plastic on which the pixels are shown and which is stacked together with other layers to form the final image. text/html 2011-01-12T17:26:13+02:00 http://wiki.meetthegimp.org/doku.php?id=lensfun&rev=1294849573&do=diff Many lenses exhibit some defects in their optical properties leading to distortions in the resulting image. Most common ones are barrel distortion, cushion distortion, chromatic abberation (ca) and vignetting. Besides getting a better (and therefore more expensive) lens to reduce them there is the way to correct these artefacts mathematically. text/html 2012-05-03T08:42:52+02:00 http://wiki.meetthegimp.org/doku.php?id=more_tools_and_techniques&rev=1336027372&do=diff Multiple exposures of the same person or scene with just some detail(s) changes can be a lot of fun, as seen in episode 44. Doing this yourself is not difficult and a lot of fun if you follow a few hints: * Shooting The most important thing is to use a tripod — this is crucial. You may be able to get away with another kind of solid object to place your camera on, like a table indoors or your car if shooting outside, but a tripod is the easiest and most reliable solution. Second issue is to set… text/html 2011-11-02T20:56:11+02:00 http://wiki.meetthegimp.org/doku.php?id=motifs&rev=1320263771&do=diff Placement Normally, you'd consider that placing the most important part of the scene in the middle of the image would be the best choice. But in many cases this is not true. A seemingly slightly off-balanced image can be much more interesting and attracting more viewers than a perfectly balanced and centered one. The most used guidelines are the rule of thirds which some cameras can even show in the viewfinder, other examples of placement are the rule of fifths and the golden sectioning, an anc… text/html 2011-12-28T00:37:54+02:00 http://wiki.meetthegimp.org/doku.php?id=noise&rev=1325029074&do=diff Unless you shoot with a very expensive camera, there will always be sensor noise. It may or may not be noticeable but it's there. Several methods and techniques exist to counter it. Noise was covered in episode 36, 62 and 63. Noise removal uses additional image information to discern between actual image detail and noise. This method requires the most work but gives the best results. text/html 2010-12-18T02:14:05+02:00 http://wiki.meetthegimp.org/doku.php?id=panorama&rev=1292634845&do=diff Panoramic images are nice to show an extensive view or a scene or place. There are basically two different approaches to create them: You can use an ultra-wide-angle fisheye or non-fisheye panorama lens or you can combine several shots of the same scene into a panoramic image. This is called Panorama Stitching. text/html 2011-06-25T23:37:35+02:00 http://wiki.meetthegimp.org/doku.php?id=plugins&rev=1309037855&do=diff Quite a lot of GIMPs seemingly core functionality is actually provided by plugins which are just pre-packaged and distributed alongside GIMP. Examples are all the filetypes except XCF and main tools like Gaussian Blur, the Curves and the Channel Mixer. text/html 2010-12-06T17:02:04+02:00 http://wiki.meetthegimp.org/doku.php?id=prepare_the_edit&rev=1291651324&do=diff Prepare the edit If you made a written plan, open it with your favorite text editor, put it on a separate desktop easily accessible (e.g. on before or after the current one) and load the initial image in Gimp. (Note: Almost all subsequent steps will only cover Gimp, but the workflow is comparable to other programs like Krita or Cinepaint) text/html 2011-09-29T18:37:17+02:00 http://wiki.meetthegimp.org/doku.php?id=recording&rev=1317314237&do=diff Aside commercially available programs like DemoRecoder (which Rolf uses), there are also numerous free solutions. Screencasting programs have to tackle three different aspect: Recording the contents of the screen, recording the audio and synchronizing both. Editing and uploading is usually done with different applications. text/html 2011-09-07T22:02:50+02:00 http://wiki.meetthegimp.org/doku.php?id=remove_objects_and_unwanted_marks&rev=1315425770&do=diff To remove unwanted or disturbing details from an image which can't be managed by simply cropping or painting over (like car license plates) there are several possibilities. Note: All of these methods leave visible or invisible traces in the image which can later on be detected quite easily (e.g. by Difference of Gaussians and Fourier Analysis in G'Mic). So, for real forging you have to try harder. Also, later post-processing steps like sharpening or curves can make the shape of removed objects … text/html 2011-02-03T15:11:58+02:00 http://wiki.meetthegimp.org/doku.php?id=rotating_the_image&rev=1296742318&do=diff There are two fundamentally different kind of rotations: Orientation and “normal” rotation. While orientation could be fixed via rotation, this is unadvisable. Note, that rotating is a degrading operation on the image, so it should only be done once and as early in the post-processing workflow as possible. text/html 2010-12-06T17:00:08+02:00 http://wiki.meetthegimp.org/doku.php?id=save_the_image&rev=1291651208&do=diff There are two distinct king of saving an image in Gimp. * Save the image (Ctrl-S) This is called quicksave and writes the image in Gimps native file format, xcf. It should be used regularly during editing an image. Gimp can autosave in specific intervalls, but Murphy dictates the last autosave will always be just before that very difficult and time-consuming step. text/html 2011-01-09T15:55:33+02:00 http://wiki.meetthegimp.org/doku.php?id=selections&rev=1294584933&do=diff Selections A selection defines to which regions of an image (or more correctly: the currently active layer or mask) changes will be limited to. This affects all tools and plugins except those that inherently change the whole image like scaling, cropping or changing the image mode. text/html 2010-12-08T00:48:34+02:00 http://wiki.meetthegimp.org/doku.php?id=separate_the_images&rev=1291765714&do=diff Separate the images After you've imported the shots e.g. from a photosession or so you'll be sitting in front of a stack of images of different technical and artistic quality. You need to sort and separate them in different categories. (Note: This is completely independent from the “usual” sorting for occasion, date, place etc.) text/html 2011-09-02T11:56:59+02:00 http://wiki.meetthegimp.org/doku.php?id=sharpening&rev=1314957419&do=diff Generally, every digital photo needs to be sharpened. In post-processing sharpening is usually the last step. It must always take place after scaling and cropping as the sharpening depends on the final pixel size of the image. Sharpening works either by enhancing the contrast of edges through subtracting a blurred version of the image from itself or by using edge-finding and wavelet math. text/html 2011-01-12T16:16:46+02:00 http://wiki.meetthegimp.org/doku.php?id=shutter_speed&rev=1294845406&do=diff Also called Exposure Time is the amount of time light is permitted to enter the camera and be collected by the sensor. The longer the time is, the more light can enter. Longer exposure times (slow shutter) lead to blurry images if things are moving through the scene while short times (fast shutter) “freeze” the movement. text/html 2012-05-13T18:41:09+02:00 http://wiki.meetthegimp.org/doku.php?id=start&rev=1336927269&do=diff Preface Bill from Belize has made a [text] about the workflow for editing a photo in GIMP. This is of course only a recipe, no set of rules and open for discussion and change. I have started to translate this into a Wiki. It's open for everybody who cares to create an account. text/html 2011-11-02T21:09:47+02:00 http://wiki.meetthegimp.org/doku.php?id=tools_of_the_trade&rev=1320264587&do=diff Several programs can accomplish different tasks at the same time, but it is sometimes advisable to use specialized software for each step in the workflow. The available programs can — roughly — be split into three major categories: * Management These are programs that download the photos from the camera or memory card and which you can use to tag, rate, sort and categorize images and export them to other programs or upload them to a photo hoster. Examples are digiKam and Shotwell Also, p… text/html 2011-01-14T19:20:41+02:00 http://wiki.meetthegimp.org/doku.php?id=whitebalance&rev=1295029241&do=diff Whitebalance defines the temperature of the surrounding light, corresponding to black body radiation. It is given in Kelvin and has high number for an intense blue sky (like in the mountains above the clouds) and low one for a cozy red mood (like at sunset or in candle light). Whitebalance defines the relationship between the three color channels red, green and blue for a given image. Every camera offers an automatic whitebalance and most have a manual temperature setting (either you can choose… text/html 2011-07-25T23:19:55+02:00 http://wiki.meetthegimp.org/doku.php?id=wiki_editing_title&rev=1311628795&do=diff wiki editing content text/html 2010-12-06T17:01:39+02:00 http://wiki.meetthegimp.org/doku.php?id=work_on_a_copy&rev=1291651299&do=diff Work on a copy If you decided to work on an image, always make a copy of the file first. Never work on the original file! Programs can contain bugs and you can make mistakes, so even in the worst case you at least have the original and can start over. This goes for rawfiles as well, while they may not be overwritten, UFraw has a button to delete the rawfile you can accidentally click.