post processing: the Gimp perspective tool is not really transforming

I have uploaded a screenshot below to illustrate the problem. I dragged a jpeg to Gimp, clicked on the perspective tool and then tried to use it … but as you can see, it's not really transforming the image. Why is this so?

Click to enlarge the image.

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apt-get upgrade will not update gimp from the ppa

I've been playing with Ubuntu Mini 18.04 LTS ISO tonight and tried to install a ppa for GIMP because 2.8 simply would not cut it. The ppa that I used is ppa: otto-kesselgulasch / gimp.

By doing apt-get update and apt-get upgrade, it shows that nothing has been updated. I installed the update manager to see if it can do it, but it says that my system is up to date.

Looking at the output of the terminal for apt-get upgrade and apt-get install gimp, one thing caught my attention, and 1 not updated. I'm not sure what exactly that means and how it can help me, I just have the feeling that it's important for this. Here are some terminal exits to start.

james @ ubuntu: ~ $ sudo apt-get update
Hit: 1 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Get: 2 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]   
Get: 3 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB]    
Hit: 4 http://ppa.launchpad.net/libreoffice/ppa/ubuntu bionic InRelease
Hit: 5 http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu bionic InRelease
Fetched 177 kB in 1 s (288 kB / s)
Reading the lists of packages ... Done
james @ ubuntu: ~ $ sudo apt-get upgrade
Reading the lists of packages ... Done
Dependency tree of the building
Reading state information ... Done
Update calculation ... Done
The following packages have been retained:
gimp data
0 updated, 0 newly installed, 0 to delete and 1 not updated.
james @ ubuntu: ~ $ sudo apt-get install gimp
Reading the lists of packages ... Done
Dependency tree of the building
Reading state information ... Done
gimp is already the most recent version (2.8.22-1).
0 updated, 0 newly installed, 0 to delete and 1 not updated.

clipping – A simpler way to select the paper picture in Gimp?

When I scan photos on my printer, sometimes it is a silly printer and it does not take out the background, especially when there is a lot of white. How would I do this in my sample photo other than the selection with the selection tool? The autoclave and the jealous harvest do nothing.

Color correction: How can I desaturate the reds in postprocessing with Rawtherapee (or Gimp)?

I took some art images in the sunlight. I used the Rawtherapee pipette to find a white balance with which I am happy, but the red one is too bright.

How can I desaturate only the red ones?

I had some success reducing the contrast, but obviously it affects the whole image.

Here is an example. Left is the original image, red is too bright. On the right is the corrected image, here obtained with the contrast set at -20 (with Gimp): red is correct, but not the other colors.

Intense red

Bucket tool based on lower layer in GIMP.

In GIMP, I want to use the cube tool to fill certain areas of my image, but I would like to do it in a higher layer instead of directly in the image.

I think I need to adjust some of the layer settings somewhere so that the cube tool recognizes the edges of the lower layer, but I can not figure it out.

Gimp – Average selection HSV values

I want GIMP to calculate the Hue, Saturation and Average value of a selection.

You could select several pixels of the desired area and read the values ​​of the FG / BG Color tongue. This would be tremendously inefficient; I have to do about 100 of these.

Preferably, it would be automagic: the reading out of the average RGB values ​​and its conversion to HSV would be acceptable, although suboptimal.

Do all the gimp color functions not work and have I tried all the suggested corrections?

Gimp is set to rgb. Only one layer of the base image. It will be reversed, but any of the color management tools does not do anything, gimpo worked 20 minutes ago, so I think it's something I did. But I have reconfigured the default settings that did not work, I simply uninstalled and reinstalled what did not work, please help! I can not do anything with colors.

GIMP. How to add a small, movable, resizeable image to a larger image?

I have a small image of & # 39; stamp & # 39; I want to put over the documents. Type of seal & # 39; they. The stamp is largely transparent, the stamped document must be displayed.

I find opening the base document and then & # 39; open as layers & # 39; the document & # 39; stamp & # 39; It brings the stamp as a layer in the first document.

But it's delineated with crawling ants, I can not fix that. And I can not find a handle to change the size. And when I move it, the whole image moves, the image & # 39; base & # 39; and all.

What am I doing wrong.

How to make GIMP 2.10 titlebar black

By default, Gimp 2.10.6 on Ubuntu 18.10 uses a dark theme. However, in a Vanilla Gnome session that uses the default Adwaita theme, or with any other light theme, the title bar is light. Is there any way to make the title bar dark only for Gimp?

Double exposure photo with Gimp.

Interestingly, while the other obvious answer is good enough for more practical purposes, averaging layers with 50% opacity does not always give the true double exposure effect. It's all due to the lack of linearity of sRGB and the fact that often our photo processing applications do not care about gamma, which works as if the pixel values ​​were bright.

So, for those interested:

On the left: superimposing images with 50% opacity in the sRGB space, ignoring gamma (this was the only option in Gimp before 2.9). The result do not It reflects the real effect of double exposure.

On the right: the same, but using the Lineal light Mode (it is only possible in Gimp 2.9 and later versions and it is not the default mode, of course, professional applications like PS can always do it). The result is similar but slightly different, especially in places where the bright pixels of one image meet the dark pixels of the other. This is simulates the double real exposure Where we add light and not pixel values.

comparing sRGB versus linear with 50% opacity