Ubuntu Open Week -Intro to GIMP - akk - Wed, Nov 4, 2009

  • utc

(03:02:38 PM) akk: Hi, all! Welcome to the GIMP session!
(03:02:50 PM) akk: I'm Akkana Peck -- I wrote "Beginning GIMP" ( and I've been involved with GIMP for 8-9 years.
(03:03:12 PM) akk: You all probably know what GIMP is, but it stands for GNU Image Manipulation Program,
(03:03:12 PM) akk: and what it does is edit images.
(03:03:57 PM) akk: If anybody has specific techniques you'd like to learn (or other questions),
(03:03:57 PM) akk: ask on #ubuntu-classroom-chat.
(03:04:21 PM) akk: If you don't have any of your own photos handy for following along during this session,
(03:04:29 PM) akk: you might like some of the ones at :)
(03:05:02 PM) akk: And a tip to start out: you may be able to drag from Firefox straight into GIMP
(03:05:09 PM) akk: (drop it over the Toolbox -- the small window with all the buttons)
(03:05:40 PM) akk: Drag-n-drop works in a lot of places in gimp (I'll talk more about that later if I have time).
(03:06:11 PM) akk: For commandline junkies (like me), you can also run gimp foo.jpg bar.jpg ... and it will open in your already-running GIMP -- that's how I most often open images.
(03:06:39 PM) akk: Any questions to start out? Does everybody have gimp running and an image loaded?
(03:07:49 PM) akk: I'll start with some really basic stuff (that still confuses a lot of people): scaling.
(03:08:02 PM) akk: You can't put your 5-megapixel image on the web -- people will hate you.
(03:08:37 PM) akk: Image->Scale Image lets you make the image a more reasonable size.
(03:08:49 PM) akk: It brings up a dialog showing the current size of the image. Bring it up and take a look.
(03:09:48 PM) akk: IGNORE the X and Y resolution fields. They don't do what you probably expect.
(03:10:03 PM) akk: Also, that menu over on the right that says pixels?
(03:10:22 PM) akk: It has two useful settings: Pixels and Percent.
(03:10:33 PM) akk: The other settings are misleading.
(03:10:50 PM) akk: You might think 'I want to print out an 8" x 10" photo, so I should Scale to that size!"
(03:11:08 PM) akk: But all GIMP knows about in an image are pixels.
(03:11:14 PM) akk:  If you don't have enough pixels, it won't look good printed.
(03:11:20 PM) akk: If you have too many, it'll be too big to put on a web site.
(03:11:41 PM) akk: (Personally I try to keep web images around 550-800 pixels, biggest dimension.)
(03:11:58 PM) akk: <mhall119|work> QUESTION: what's the best scaling interpolation?
(03:12:22 PM) akk: That's something people argue about. Either Cubic or Lanczos is good
(03:12:37 PM) akk: but Lanczos has some problems in certain situations -- Cubic works pretty well everywhere.
(03:13:12 PM) akk: I usually type my number (600 or whatever) into the Width field then hit Tab
(03:13:12 PM) akk: and the other field adjusts automatically. Then click Scale.
(03:13:29 PM) czajkowski: 20:13 < SoftwareExplorer> QUESTION: Where does Lanczos not do well?
(03:13:31 PM) akk: If you want to scale in only one dimension (not have the other field auto-adjust)
(03:13:47 PM) akk: you can click the little chain-link linking the two fields.
(03:14:18 PM) akk: I actually don't remember the details of where Lanczos breaks down. :) Would have to look it up. Ask me again after the class and I'll find it.
(03:14:41 PM) czajkowski: 20:13 < Jesi> Question: I love GIMP, and actually think it's much better than photoshop, but GIMP is so underrated and many people say they don't like it, but often I find these  people don't give it a chance...they either feel intimidated by it, or simply don't like it because it's not Photoshop and often they don't want to take the time to
(03:14:46 PM) czajkowski:  learn a new prgram (that's understandable), how would yuou go about encouraging someone
(03:14:49 PM) czajkowski: 20:13 < Jesi> to give GIMP a try?
(03:15:38 PM) akk: I agree with Jesi on that. At the same time, I can understand users not wanting to learn a new UI.
(03:16:22 PM) akk: It's possible to substitute a set of key bindings that make GIMP a little more like PS ... but I don't generally recommend that since the rest of the interface is still pretty different.
(03:16:52 PM) akk: Likewise, using something like Gimpshop (a hacked build of gimp) usually doesn't work out very well.
(03:17:14 PM) akk: So I guess I'd just stress to them that learning a new program always takes a bit of time, but can be worth it in the end.
(03:17:43 PM) akk: Okay, I think I'm caught up on questions.
(03:17:50 PM) akk: After you Scale, you get a ridiculously tiny image in a huge window.
(03:17:50 PM) akk: You'll probably want to zoom it to 100%.
(03:18:02 PM) akk: At the bottom of the image window you can see your zoom factor (e.g. 50%, 33%, 100%).
(03:18:16 PM) akk: It's a menu, so you can choose any zoom right there, or from View->Zoom.
(03:18:26 PM) akk: You can also zoom in/out with the +/- keys.
(03:18:45 PM) akk: Or type 1 at any time to zoom to 100% (that's great if you're previewing something you just scaled for the web).
(03:19:00 PM) akk: +, - and 1 are great key bindings -- I use them all the time.
(03:19:16 PM) akk: But after you zoom, the window is probably the wrong size.
(03:19:23 PM) akk: View->Shrink Wrap can fix that, or you can set the two prefs under Image Windows, Zoom & Resize Behavior.
(03:19:42 PM) akk: (I always set those prefs -- it drives me crazy to have a small image in a big window.)
(03:20:16 PM) akk: <itnet7> QUESTION: Is part of the problem in learning from tutorials and such for new gimp users the differences found within options/locations between linux/windows or are the environments relatively the same?
(03:20:49 PM) akk: GIMP is almost identical on different platforms -- the only difference is in window manager behavior
(03:21:19 PM) akk: and platform-specific bugs, e.g. Apple's X11 doesn't support drag-n-drop.
(03:21:35 PM) akk: So tutorials should usually work well across platforms
(03:21:50 PM) akk: though not always across GIMP versions -- the UI has been changing lately and it will change again in 2.8.
(03:22:18 PM) czajkowski: 0:22 < mhall119|work> QUESTION: what interface changes are coming in 2.8?
(03:22:55 PM) akk: The big deal right now in GIMP 2.7 dev is "single window mode", where it will be possible to have everything (including all images) in one big window.
(03:23:27 PM) akk: That's something Windows users ask for a lot, partly because they're used to MDI and partly because Windows doesn't deal as well with lots of little windows as Linux window managers do.
(03:24:03 PM) akk: There are also a lot of drawing improvements, esp. for tablets ("brush dynamics")
(03:24:16 PM) czajkowski: 20:22 < faberglas1> QUESTION Can you reccomend any web tutorials or books for GIMP?
(03:24:33 PM) akk: and things like several tools combining into one, like all the transform tools (rotate/scale/perspective/etc).
(03:25:15 PM) akk: Well, I'm biased but I kind of like my book. :)
(03:25:54 PM) czajkowski: 20:24 < the_madman> QUESTION: A lot of my friends in college use Photoshop because they are graphics designers or artists, using tablets. One of the features that makes Photoshop  so appealing to them is the ability to change the brush, e.g. the amount of faded pixels from the edge, pressure etc. While I've seen these features available
(03:25:54 PM) akk: There are TONS of good web tutorials, and even video tutorials like "meet the gimp".
(03:25:59 PM) czajkowski:  in Krita, it fels less mature in comparison to the Gimp. Doess the Gimp support these
(03:26:02 PM) czajkowski: 20:24 < the_madman> configurable brushes in some way I haven't seen?
(03:26:24 PM) akk: I've collected some of the good tutorial collections at:
(03:27:16 PM) akk: GIMP does support some of those brush operations -- in 2.6 there's a "Brush dynamics" tab in the paint tool options
(03:27:27 PM) akk: and Brush Dynamics is getting a lot smarter and more flexible in 2.8.
(03:27:57 PM) akk: It should be a lot better for artists wanting to draw with tablets.
(03:28:27 PM) akk: But even in 2.6 it can do some of that if you experiment with tool options.
(03:29:26 PM) akk: Okay, I was going to talk about brightness/contrast next, but time is flying by so I'll skip most of that unless people are dying to hear about it.
(03:29:47 PM) akk: I'll just mention that in the Brightness/Contrast dialog there's a feature new in 2.6: "Edit these settings as Levels"
(03:29:53 PM) akk: and from Levels, you can Edit as Curves
(03:30:09 PM) akk: which is a really cool and useful feature, so play with it if you want more control than regular brightness/contrast.
(03:30:53 PM) akk: A couple of questions I missed: <Xiella_> QUESTION: brush dynamics, do you mean rotatable brushes without using a plugin?
(03:31:27 PM) akk: Brush rotation is different from dynamics, but my understanding is that it will be in 2.8. (I hope that's true.)
(03:31:41 PM) akk: <Jesi> Question: You've been using GIMP for several years, and most likely keep up with the roadmap, what can we expect from GIMP in the future (this is an "intro" and I don't expect this question to answered unless time permits :) )
(03:32:41 PM) akk: Because of time I won't try to give a detailed answer, but there are a lot of UI changes underway (there's a "gimp UI brainstorm" blog where some of this gets discussed).
(03:34:32 PM) akk: Now, a tip about rotation (this is another section that I'm going to cut shorter than I'd planned):
(03:35:02 PM) akk: most of you probably already know the free rotation tool (just after the Crop tool in the toolbox)
(03:35:15 PM) akk: Click on the tool, click in the image, drag around and it rotates.
(03:35:41 PM) akk: You can hit return when you're happy with the rotation -- no need to use the dialog that pops up (or use ESC to cancel).
(03:36:01 PM) akk: But sometimes you have a photo where the horizon isn't level
(03:36:08 PM) akk: like
(03:36:25 PM) akk: Instead of just rotating and trying to guess when it's roughly level
(03:36:54 PM) akk: you can go to Tool Options (usually right under the Toolbox)
(03:37:20 PM) akk: and look for the third option down, "Direction".
(03:37:27 PM) akk: Set that to "Corrective (Backward)".
(03:37:27 PM) akk: Then set Preview (farther down) to "Grid".
(03:37:49 PM) akk: Now, when you click in the image, drag so that the grid lines up with the horizon.
(03:38:04 PM) akk: Then when you hit Enter (or click Rotate), it'll rotate so that the horizon is level.
(03:38:20 PM) akk: I can't believe how long I went wishing for something like that and not knowing it was already there.
(03:38:50 PM) akk: BTW, there's been some discussion in -chat about rotating brushes to follow the direction of pen movement.
(03:39:17 PM) akk: That *may* make it into 2.8 (I hope, I hope) but it's actually possible to do that now with animated brushes.
(03:39:39 PM) akk: There's an "ant" brush somewhere on the web where the ants rotate following the direction of the mouse as you draw.
(03:39:51 PM) akk: But there's no documentation on how to make brushes that do that, so it's hard to make new ones.
(03:40:27 PM) akk: Okay, how is this going? Am I going too fast, too slow, too basic, not enough basic stuff?
(03:41:00 PM) akk: <johanbr> QUESTION: Have any usability studies been done with GIMP? If so, what were the results?
(03:41:00 PM) czajkowski: 20:40 < johanbr> QUESTION: Have any usability studies been done with GIMP? If so, what were the results?
(03:41:09 PM) akk: heh, sorry, czajkowski
(03:41:51 PM) akk: GIMP has a UI person in charge of the design, peter sikking
(03:42:09 PM) akk: who has sort of looked at usability though I'm not sure there have been actual formal studies.
(03:42:33 PM) akk: (I'd like to see some larger usability studies myself.)
(03:43:07 PM) akk: Question: Now my rotated pic has cricket borders, how to correct that?
(03:43:21 PM) akk: When you rotate, you end up with transparent edges. To get rid of them, use the Crop tool
(03:43:43 PM) akk: (the icon looks like a scalpel or x-acto knife) and drag in the image to include only the inner part.
(03:43:53 PM) akk: There's no way to have Rotate do that automatically, unfortunately.
(03:44:32 PM) akk: QUESTION: when I take a screen shot and want to add an arrow or circle something how do I do that?
(03:44:37 PM) akk: Great question!
(03:44:57 PM) akk: First, you definitely want to use layers for that.
(03:45:19 PM) akk: So you want to make sure your Layers dialog is visible. It should say Layers -- if you don't see a window like that,
(03:45:30 PM) akk: Windows->Dockable dialogs->Layers will bring it up.
(03:45:57 PM) akk: Then create a new layer: that's the New Layer button at the bottom left of the Layers dialog.
(03:46:19 PM) akk: Now you have a new transparent layer to draw on. that way, you can draw as much as you want but your original image is still safe.
(03:46:41 PM) akk: Now choose a drawing tool -- I usually use the Paintbrush.
(03:47:19 PM) akk: In the Paintbrush's Tool Options, there's a place to choose Brush.
(03:47:38 PM) akk: By default it's too big, so you probably want a slightly smaller brush (one of the small circles).
(03:48:27 PM) akk: Then you can scribble/draw on your layer.
(03:48:43 PM) akk: <mhall119|work> akgraner: for squares and circles, use the appropriately shaped selection tool to define it, then Edit->Stroke Selection
(03:48:48 PM) akk: (saved me some typing there :)
(03:49:04 PM) akk: and for straight lines, click on the start point, then shift-click on the end point.
(03:49:26 PM) akk: And that just leaves arrows -- making a good looking arrowhead is tricky
(03:49:49 PM) akk: and what I do is google for gimp arrow brush and download an appropriate set of brushes that include a bunch of arrowheads.
(03:50:09 PM) akk: <toobuntu> QUESTION: How can one smudge personally-identifying information out of a screenshot?
(03:50:28 PM) akk: There's actually a tool called the Smudge tool that works well for that. I've used it on license plates and such.
(03:50:46 PM) akk: You could also use the Clone tool or the paintbrush, but Smudge is usually enough.
(03:51:22 PM) akk: Running out of time, and I had two sets of things I really want to talk about, so let's see if I can get them both in.
(03:51:38 PM) akk: First, selection. That's how you select part of an image (e.g. just the koala and not the background)
(03:51:43 PM) akk: so you can paste it somewhere else.
(03:52:16 PM) akk: GIMP has a tool called the Free Select tool (or Lasso tool, from its toolbox icon)
(03:52:27 PM) akk: that was useless until 2.6 but is now awesome :)
(03:52:46 PM) akk: You can draw freehand with it, but you can also do click click click to connect-the-dots.
(03:53:30 PM) akk: I recommend turning on "feather" to make the edges of the selection slightly fuzzy
(03:53:44 PM) akk: (more fuzzy if you're trying to select a really furry animal, so you don't have to select individual hairs).
(03:54:15 PM) akk: But the real trick to selection is: don't worry too much about getting it right as you're connecting the dots with the Lasso tool, because you can fix it later.
(03:54:33 PM) akk: In your image window, at the lower left corner, there's a tiny inconspicuous button
(03:54:33 PM) akk: just to the left of the scrollbar
(03:54:33 PM) akk: marked only by a black and white dotted-line square.
(03:54:41 PM) akk: If you hover over it, it says "Toggle Quick Mask."
(03:54:53 PM) akk: The button changes to a red-outline square, to show you're in Quickmask mode
(03:55:01 PM) akk: and the image view changes to have red everywhere that's NOT selected.
(03:55:01 PM) akk: In the parts that ARE selected, you can see the image (no red mask).
(03:55:10 PM) mode (+v mgunes ) by jcastro
(03:55:22 PM) akk: Once you're in Quickmask mode, painting black makes things NOT selected (red); painting white makes them selected.
(03:55:50 PM) akk: So you can zoom way in, to 500% or whatever, and get your selection details perfect.
(03:56:00 PM) akk: Click on the Quickmask button again to go back to normal mode.
(03:56:30 PM) akk: Eek, 5 minutes. Okay, the other thing I want to get in is two really cool GIMP UI tricks.
(03:56:43 PM) akk: First,  dynamic key bindings. First you have to turn them on.
(03:56:43 PM) akk: Edit->Preferences, Interface, and check the box labeled "Use dynamic keyboard shortcuts".
(03:57:14 PM) akk: Now, if you bring up a menu, hover over an item and press a key (with a modifier, like shift/ctrl/alt)
(03:57:22 PM) akk: it will assign that key to that item.
(03:57:38 PM) akk: So e.g. I can click on Colors, hover over Curves (because I do Curves a lot) and type Shift-C
(03:57:48 PM) akk: and now every time I do Shift-C, the Curves dialog comes up.
(03:58:21 PM) czajkowski:  QUESTION: How many people work on the GIMP code?
(03:58:35 PM) akk: Second is tear-offs -- if you have a menu you're using a lot (say, lots of things from Filters->Map)
(03:58:49 PM) akk: if you right-click in the image, you'll get a copy of the regular menubar menus
(03:59:08 PM) akk: only every menu has a dotted line at the top -- click on it and that menu "tears off" and stands as a window on the desktop.
(03:59:40 PM) akk: GIMP is a surprisingly small project. I'd estimate something like 5 active developers, maybe another 5 or so who contribute small amounts fairly regularly
(03:59:56 PM) akk: and then maybe double that number who contribute less often.
(04:00:20 PM) akk: Okay, I guess we're done. Thanks, all!

MeetingLogs/openweekKarmic/IntroGimp (last edited 2009-11-04 21:03:29 by pool-71-182-105-84)