GIMP/C2/Rotating-And-Cropping-An-Image/English

From Script | Spoken-Tutorial
Jump to: navigation, search
Time Narration
00:22 Welcome to the spoken tutorial of Gimp
00:26 I am a teacher and my school is next to the river Weser, in Bremen, and on my way to school i take some pictures.
00:36 This year it was March, and the sun was up for just 2hrs or so
00:42 It was foggy and the tide was high and a ship came around the corner and disturbed some birds resting on water.
00:55 Before I start editing this image I want to tell u in brief about using RAW for your real photography.
1:05 If I had shot this image in JPEG, I would have had 256 steps of brightness for encoding it.
1:16 You see it’s nearly black and white, a bit bluish greenish tint and basically it’s only gray
1:29 And with JPEG you have 256 different values of gray,
1:37 Zero for black and 255 for white.
1:42 And in this image there is no white and only a bit black. So only a small space of this room is used. I’ll show you how must later.
1:56 I had shot this image In RAW and my camera stores raw images in 12 byte data format
2:05 So I have 12bit instead of 8bite and so 4,096 steps of gray instead of 256
2:15 And you can see the difference here. This is the image I have got out of the raw converter after spreading the values and here I have 256 different values of gray and now I can start to edit the image.
2:39 In this image there r more details saved as compared to the 1st one. This is the 1st image I remember and this one I have got after conversion.
2:50 The 2nd image is a good base for doing post processing which results in a picture which has the mood of 1st image but looks better
3:08 If u want me to teach u raw converter with an open source or atleast a free tool for Windows, Linux and Macantosh then u can drop me a mail or u can comment on my block.
3:30 Now I have opened the two images in the GIMP so let’s us have a look at the histogram of the 2 images
3:38 The histogram is hidden in the image dialog, But we have 3 different way of reaching the image dialog, 1st way is on tool bar, 2nd way is to click on Access The Image Menu here & click on dialogs, and the 3rd way is simply right click into the image then dialog, and histogram. I take that way most of the time.
4:17 Here’s the histogram of the 1st image. Make it a bit bigger and here you see the distribution of different pixels of the different colors in the image.
4:32 Digital image is similar to painting by numbers. When u zoom into the image u see a lots of little tiles and each of this tiles has a different color which is called as a pixel and each color is defined by a value and I can show you these values here with the help of color picker.
5:06 When I use colour picker I get the values for red, green & blue. In this image the value of red is a bit less than green and blue. Green and blue have nearly and exactly the same value.
5:23 OK painting by numbers is digital photography
5:31 In this image here I have nos form 0-255, and we have a really dark part here but I don’t think it’ll make into the final image.
5:51 I think the real part of the image starts here at around 80 and the brightest part of the image is here at around 200.
6:04 So we have room from 0 to 256, but we only use 120 here which is less than half of data which we could use. And because of that a lot of information of the image is lost here.
6:27 The GIMP uses only 8 bit data but there are some other programs which use 16 bit data for the images and allows us to use the whole data from the raw image.
6:45 The work is in the process but I don’t think it’ll make in GIMP 2.4, perhaps we will have to wait for something like 2.5.8 or something, so that we can use it 16bit data in GIMP.
7:05 I will inform u about this as soon as it happens.
7:10 Let’s have a look at the histogram of the 2nd image. As we can see here there is more data in this histogram as compared to 1st one but the form of the curve is identical. U compare these 2 histograms.
7:32 Details in the 2nd image is spread out so the problem I have to solve here is to make the 2nd Image compressed like the 1st one but it should have a bit more of the details and it should have a bit more of contrast like this one in the 1st image.
7:52 Before I start working with this image, I want to show you a thing that I found out about the gimp user interface while recording the last tutorial.
8:06 When you press tab into the image window, the tool box here vanishes and helps me in getting the image as big as possible and I can switch the tool box on and off as per my requirement. So I can see it better what I am doing here and u can also see it better.
8:40 Before I start the editing the image I have to change some settings. So I go to file, preference and here I go to window management, and choose the option here, keep above for the tool box and keep above for the docks and leave the rest of options as it is.
9:09 After I press ok, the GIMP works as advertised.
9:14 I can select the tools from the tool box and get all option of the tool I have and selected. I can click back into the image and use tab to switch the tool box on and off.
9:29 The first thing to do is to check if the image is level.
9:33 In this image, there are no reliable man made structures here, so I can’t use the grid method to check if the image is straight which I should u in the first edition of meet the gimp
9:47 The surface of the water is a very good clue. But we don’t see the horizon here and the streaks on the water are also a bit misleading. This here is not the horizon but just a curve in the river
10:02 So I don’t have a real clue where to set a ruler and check the horizon. I just have to relay on my eye which I don’t think is the worst way to do something in photography.
10:19 Now I select the rotate tool and I choose normal forward instead of corrective backward and I set in preview as image and not the grid. Ok click into the image.
10:42 Here in the center there is a point called center of rotation and around that point the Image will be rotated and here is the dialog where we can set the angle about which we want to rotate the image
11:00 Here I have a slider which can help me in rotating the image but u can see that it is difficult to handle and I don’t think I have to tilt the image this much.
11:16 So let’s go back to zero here and now I just use the style here to rotate the image. I think the image is bit tilted toward right so I have to rotate the image to the left i.e. counter clock wise so I have to get here negative values. So I keep on changing the angle till I get the correct and straight image.
11:55 This is a bit too much I think
12:00 So I set it the angle for -0.25°
12:07 Pull this window in back and click on rotate and wait for the result of this operation.
12:19 Next step cropping
12:23 In the image I want to have of course the ship, the water and these birds here. And I don’t want to have in the image is this grass here, this part here and I m really not sure if I want to have this bank of the river in my image.
12:46 And I think I will crop this part of image because later I want to have the darkest part of the image i.e the birds here, the ship and then the trees, the bank behind the ship, and lastly the water and sky.
13:05 And this part of the image is too dark
13:11 I want to zoom into this part of the image as I want to include as much as possible the part of the river but nothing of the bank so I zoom into the part of the image her by pressing the hot key z.
13:33 OH... here’s another bird flying. So I go to the left side and I pull over the ruler close to the bank and leave it here. And press Shift + ctrl + E which brings me back to the image
13:49 Now I have to select the crop tool and set some options in it.
13:54 I want the fixed aspect ratio 2:1. And in preview I set rule of thirds for little bit of help which will provide me some helpful lines
14:21 OK I am set. And I start the cropping from here and I pull it over to the other side of the window. Right up to the border. Now I have my maximum possible crop because I don’t want to pull it over to the right.
14:50 Let me see what all is included here.
14:56 Here it is a group of bird and single bird appear here. Now u can click the rulers away
15:09 On the lower part of image there is water but I think it’s no enough water in it and too much sky is included. I can lose this single bird up here because I want this group of birds to stay in the image.
15:26 Now I simply pull this down and I think this looks quite nice
15:36 To check my work I select rule of thirds. My eye isn’t so bad because I divided the image into 3different parts i.e the water, the trees and the sky. The ship is the one of the point of interest
16:01 This group of birds is second point of interest and this one is nice 1/9th of the image.
16:10 I think this will work so I click in the image to crop. Press tab and shift + ctrl +E to enlarge the image.
16:22 I think we have started very well with the cropping of the image and what else to do with this image, I will show you in the next show.
16:32 Oh before I say good bye, I should save the image which I should have done much earlier. I save the image as Fog.xcf and ‘xcf’ is the extension of GIMP’s own file format and it contains lots of helpful information of layers and undo information and much more from the GIMP.
17:12 I would like to hear from you. Tell me what you liked, what I could have made better by mailing on to info@meetthegimp.org, or go to fore room of tips from the top floor and leave a comment there.
17:30 More information is available at http://meetthegimp.org
17:40 This is Hemant Waidande dubbing for the Spoken Tutorial project
17:50 Good bye and hope to see you next time around.

Contributors and Content Editors

Chandrika