March 7, 2005

Ask the Guru: Making a Collage

Filed under: asktheguru — Tags: — Eric Jeschke @ 10:45 pm

Making a collage

Hi Everyone…I don’t know how I missed this group when searching for a GIMP support group. I am new to the program but I really like it. The problem is this…I am making a collage and I am trying to resize the pictures and paste them into the collage. I know the steps to make the collage in general, but the sizing of the images is driving me nuts.

I made a new 8×10 canvas. I resized 3 images (or so I thought I did) to 3×5. I have one image at 8×10 (again so I thought). I am trying to put the 8×10 image on the 8×10 canvas and lower the opacity to 60% . I then want to take each of the other 3 images and put them on the 8×10 image which is on the 8×10 canvas. When I check the image properties they are all the sizes I made them, but when I copy and paste them on the 8×10 canvas, they are still huge or only part of the image shows up. I tried to do a web search to find the answer, but I don’t even know how to title my problem. If anyone here has even a remote idea of how to help, please post. I’d really appreciate it.

Thank you!!


Hi Lisa,

Here is how I would go about it.


Open your “background” image.
Set the image print size (Image/Print Size).Choose a printing resolution that gives you approximately the size you want. In this case I used 240 PPI because I know that will give me a nice sharp print.

If you highlight one of the resolution fields, type a value and then hit TAB, you should see the width and height change.

Remember the PPI you chose.

If you are going to dial down the opacity, you really need something behind the image that will show through. If you want a kind of gauzy effect you can just put an opaque white background there.To do that I duplicated the Background layer, and renamed it “Main Image”. Then I selected the Background layer in the Layers dialog, chose the bucket fill tool from the toolbox, switched to a white foreground, selected all in the image (Select/All) and clicked in the image to fill the Background with white.

I then selected the Main Image layer and dialed the Opacity of the layer down to around 75%.

Finally, add a new layer on top of the image using the new layer button in the Layers dialog (this will be for the overlaid images).

Open up another image that you want to place on the main image to form the collage. Complete any image editing work you want to do on it first.Choose Image/Scale Image (one of the nice things about the GIMP is that it uses different dialogs for resampling and setting print resolution, something that confuses so many folks in Photoshop because it only uses one dialog for both).

Set the units that you want the resulting size of the small image to be (in this case I used “inches”).

Put in the same resolution that you used earlier (in this case 240).

Set interpolation type to “Cubic” for best quality resampling.

Now dial in the size of the longest dimension you want the small image to be. In this case I wanted 3 inches wide, so I highlighted the width parameter, typed in 3 and hit TAB. The other dimension will be calculated. Underneath the width and height you can see the dimension that the image will be in pixels after downsampling (here 720×540).

Click “Scale”. The image will be downsampled.

A sharpening step here would be wise (Filters/Enhance/Unsharp Mask). In this case I didn’t bother.

Finally, Select/All and Edit/Copy.

Go to the collage image and Edit/Paste. Select the Move tool from the GIMP toolbox and move the image to just exactly where you want it.In the Layers dialog, anchor the image.


Repeat the last step with other images to be pasted.

This is a pretty quick and unpolished example, but it should convey the general idea. You could obviously do lots of fancy things to the small images (borders, drop shadows, etc.) before downsampling and pasting them into the collage.

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