I’ve tried really hard to make the GIMP work for me. Four months later this is the result (click to interact).
Setting The Stage
This is a typical 360°x180° full spherical panorama. I used to shoot a lot of them until last year. It’s six fisheye images, aligned and warped with Hugin. The equirectangular panorama of 8000×4000 pixels (low resolution for today’s standards) requires some editing.
My editing workstation is dual boot Windows XP and Ubuntu 9.10 (alpha). 8GB RAM. The two systems have equally large partitions (20GB). I usually use a common “workspace” partition for data and temporary files (if the application supports such a setting) and/or work on the network (not really convenient in Ubuntu – the samba mounts don’t show up in many file dialogs).
I’ve procesd hundreds of similar projects, although this is the first time I use GIMP for the post processing. On Windows XP I still use Photoshop CS2 – can’t find a good reason to spend money on Vista / CS4 upgrades.
Opening the Images
Ideally, Hugin should produce a multi-layer document automatically. Unfortunately we don’t have this function in the GUI yet. There are workarounds: nona can output multi-layer tiff; tiffcp can create a multi-page TIFF; tif2xcf can create a multilayer XCF.
Whatever the workaround, GIMP opens the image flawlessly. Photoshop CS2 can’t open multilayer XCF and does not open multi-page TIFF correctly. First round goes to GIMP.
Working with layers is one of two key functionalities in the process (masks are discussed further below). And the layer’s functionality of GIMP is confusing and inefficient.
The one cool function I found was that an image file can be opened as a layer. It’s odd, it surely help as a short cut, but does not compensate for the rest. My experience went downhill from here on.
I often move/copy layers between documents. In Photoshop this means right-clicking on the layer, selecting duplicate in the context menu and selecting a target document. In GIMP, duplicate layers go automatically in the same document.
I can use copy&paste to move a layer from one document to another in GIMP (in Photoshop too). But the GIMP operation is encumbered by unnecessary extra steps and added complexity.
The first thing that I notice when I paste a layer in another document is a special layer. It does not go away and does not let me do anything until I explicitely press SHIFT+CTRL+N (the “New Layer” command). Why a new layer command can’t be made implicit is beyond me. The explanation says that “Floating selections are a rest of the time when GIMP did not use layers. They have no practical use, but you must know what you have to do with them.”
Another drawback of how layers are processed in GIMP is that when a layer does not have the same size as the document, it is simply centered on paste. I often copy & paste the nadir cap (the LGM logo in this case) between two documents (of same size). It is a long and thin layer, aligned with the bottom of the document. To do the same thing in the GIMP, I had to first re-size the layer to the dimension of the document and then copy & paste it.
Enabling and disabling layers’ visibility is the same in the GIMP as in Photoshop. But enabling and disabling layers’ masks is easy in Photoshop (simply click on the mask) while in GIMP I must go through a context menu.
And don’t get me started on the inefficiency of GIMP’s context menu. Long and mostly irrelevant because it mixes Layer context with Mask context. Compare it with Photoshop’s screenshots below (far from perfect, but shorter and better targeted at the context under the mouse pointer).
I work with many documents open at the same time. When I minimize a document’s window, I’d expect that selecting it in the Layers palette would make it visible again, or at least tell me that I’m trying to look at some invisible thing. I got no feedback and wondered where in my chaos is the window gone?
A few times the system got unresponsive and then ended up out of space. I found out that ~/.gimp/.gimpswap was eating up all of my disk space, despite my attempts to divert all disk space usage to the extra large “scratch disk”.
I still feel very awkward interacting with the GIMP. Much of this may be because I don’t know the software as well. I’m self-taught in Photoshop and I don’t recall having had such a hard time with it, though.
I find that the GIMP imposes time-consuming steps on me. I won’t stop complaining about how stupid it is to discard user’s entry in the layer’s name if I don’t hit the enter key before moving on to the next operation. I’m renaming layers a dozen of times when processing a document, and this means that even if I do things according to how they should be done with the GIMP, I am a dozen keystrokes slower than performing the same operations in Photoshop.
It does not seem much, but it adds up, like the longer distance to move the mouse pointer down the context menu of the layer – it should not be too difficult to adapt the context menu to its context, and display a different menu if it is activated on the layer’s thumbnail or on its mask?
The positive surprise is that I can drag and drop the layer’s icon on another document and it works. I still prefer to do this kind of operation with context menus (or better: keyboard shortcuts) because I have to make less mouse movements to achieve the same result.
Zooming and panning are also important function for me – when 8000×4000 is a low resolution document, being able to smoothly zoom and move around the image is critical. I love GIMP’s navigator in the corner of the window, pictured above. Maybe there is a way to make the thumbnail on which I am navigating larger?
When editing the above screenshot I found what may be a bug: I set the rectangle selection tool to a fixed size of 468×468 but the image that came out is 468×467. Details? Details!
So many programs do zoom in and out with the mouse wheel. Why not the GIMP?
Masks and Brushes
The next tool I’m using a lot are brushes – in connection with masks – to decide which of two underlying images to reveal. I find the limitation of the scale from 0.01 to 10.00 too narrow – it forces me to change Brush to often – and so does the lack of a slider to determine the fuzziness / hardness of the brush. I know there are advanced settings in the dynamics, but in Photoshop I get around without it, why should it be more difficult in the GIMP? I would like to choose one single shape and then determine its size (up until the whole document), the fuzziness of the borders, opacity and the like with sliders, rather than having half a dozen brushes of the same shape but different size to choose from.
Also the movement of the brushes feels less smooth than in Photoshop.
The clone brush is another tool often used in this kind of work. And this one looks and feels like an improved Photoshop clone. Where in Photoshop CS2 I have to select an input layer and it is cloned only from that layer, I got the impression that in the GIMP it is what is visible that is cloned. But maybe it was just an impression and I was cloning the main image. By this time it was late at night of my umpteenth attempt at getting this panorama done with the GIMP. So I declared the quality as acceptable, saved it, and pushed it through my usual processing (overnight batch) into an interactive panorama.
I wish I found a way to quickly identify layers. I did not.
“Merge visible layers…” seems available in the layer context menu only. In the main menu Layer there is a “New from visible” command, but it is not exactly the same. And… shortcuts!
The export dialog when saving tiff or jpeg is somewhat confusing, but at least the most important information is clearly visible: nothing destructive happens to the original image.
I processed this panorama at 8bit depth. The GIMP still does not support 16bit or 32bit. So much for HDR.
I still have a couple of images of the GIMP team from LGM to process (and I also did not process the panorama of our own Hugin team yet!). On one side I’d like to post process them on the GIMP. On the other hand, I am still at least 4x faster with Photoshop and I prefer the results. My inefficiency on the GIMP justifies only part of the delay. Another justification is that this is unpaid, work, like Open Source. And in the past four months I have been scratching other itches. I don’t know if I’ll bring up enough motivation to use the GIMP for the next one, nor when I’ll do it.
For me, the GIMP remains a marginal tool in the toolbox. I’ll use it to have access to MathMap; and for minor things like screenshots cropping and resizing (where its drawbacks are not all too significant). But I’ll keep working with my good old Photoshop CS2, and put aside some money for the upgrade when I buy a new camera.
Filed under: GIMP