We have seen that superimposing the two images implies that we cannot see both at the same time. Remember that everything that you do on GIMP will be applied to the selected layer! You should always check whether you are applying your effects to the right image. To delete all the content of a layer, select it and then click on the red “x” icon. You can also turn on (or off) the visibility of a given layer by clicking on the small eye icon to the left of it. You can easily alter the order of the layers by dragging them up or down inside the “layers” window, or by selecting the layer and using the “up” and “down” arrow icons at the bottom of the window. Note that the background of each image is white, and not transparent.

This means that we cannot see “Graph A” because “Graph B” is on top of it. The images are drawn on the screen in a top-to-bottom order. If you do not see a “layers” window opened, go to Windows > Dockable Dialogs > Layers. What really happens is that the second one is superimposed onto the first one, which you can see in the “layers” window, as shown below. If you have dragged the files to your interface one after the other, you have noticed that, when opening the second one, the first one “disappears”. Remember you can download the images from this tutorial and try it yourself! Layer order and visibility Open your GIMP and drag both onto your interface. What if you needed to merge them in the same image for your publication?Īs they have exactly the same axis, it should suffice to add one on top of the other. Just keep in mind that you cannot see through the layers, unless they are transparent - as with a paper pile. This implies that effects can be applied independently to each layer, which can turn out very handy, as we will see throughout the tutorial. what's the correct way to get the white (or any color) background pixels to be made transparent - and preserving anti-aliasing in the process? It's easy in GIMP, but I haven't found how to do it in any version of Pixelmator.You can picture layers as independent sheets of paper, all piled up on top of each other. what is the correct way to change the 'white' (or any color) so it's transparent, and it preserves the full anti-aliasing in the same way as GIMP? If I use masks, I can get _some_ anti-aliasing, but it's not the same anti-aliasing as the original, with the difference between the original and the 'mask to transparency' shown below: The gray pixels on top are a problem, because they can be visible if put on a black background, like so: The image below has 'gray' pixels on the top of the text, and the bottom loses all anti-aliasing: As far as I've been able to use it, masks have the same problem too. With Pixelmator, I seem to have to choose between less effective options, where I either end up using the select color tool, which will select too much (or not enough) of the black text - either leaving 'grey' pixels from anti-aliasing, or removing the anti-aliasing altogether. (If you put a black background behind the layer, it stays all black, because there are no 'white' pixels there - there are only the black and alpha/black pixels: With GIMP, it just works.Įxample: I start with the following (zoomed in) anti-aliased image:Īnd a couple of clicks in GIMP, and I get an image with the White changed to transparent - and the anti-aliasing remains correct. You'll have to zoom in quite a bit to see any of what I am trying to show.Īlso keep in mind, the color may be any solid color - blue, heliotrope, whatever. Gimp has a 'Color to Alpha' option, which is useful to easily remove a colored background from an image, while also preserving anti-aliasing. I'm liking Pixelmator, but there's one feature from GIMP that I'm missing - and I'm not quite sure how to do the same thing in Pixelmator.

Gimp replace color with transparent