On 18 Oct 2019, at 03:29, Helmut Jarausch via gimp-user-list wrote:

I have a dumb photo lab (which offers very good prints with a new Canon printer). They offer prints of size 7in x 5in. I have several images which are quadratic in size. Now I have to "fill" my image with a (say) grey area left to it.

What I do:

1. Open image in GIMP 2. Select Image/Canvas Size
3. Enter something like width 700 and height 500 in the size boxes, and then click the link icon to lock the aspect ratio. Then enter the true height of your image in the Height box. 4. Use Offset settings or Center button to align your image on the canvas as required. 5. Choose Resize Layers, All layers. Choose Fill With, Background Colour (or whatever). 6. Click Resize.

I create a new image (filled with grey 868686) with the same height but a width of height x 7 / 5 I copy paste my image into this new image, move the floating selection exactly to the left (which is quite tedious to do exactly)

If you want to align a layer with the edges of your canvas, or centre it on the canvas horizontally or vertically, take a look at the Alignment tool (it’s in the default toolbox, at least on my OS/X download).

On 10/17/19 6:29 PM, Helmut Jarausch via gimp-user-list wrote:

I copy paste my image into this new image, move the floating selection exactly to the left (which is quite tedious to do exactly)

Use "File>Open as layers" to load the image over the grey background image. This will likely be faster (and the image will be aligned to the left).

Or when you have loaded your square image, use "Image>Canvas size", and increase the width (you can just add "*7/5" at the end of the width, Gimp will compute the value). Then you add a background layer.

"View>Snap to canvas edges" is also useful to align layers with the image sides.