GIMP Version: 2.10.38
Operating System: Windows
GIMP Experience: New User

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Hello, I have a picture of my house and I want to add a large decoration to the front of it but I want to make sure the dimensions are correct on both the house and decoration (2 different pictures). In Sketchup I can import a picture and then choose a point (say the top left of the front door) and measure over 36" (the top of the other side of the door) and hit enter and the whole picture will scale up to accommodate the 36" I type in. I want to be able to get both of these pictures scaled up 1 to 1, is that doable in Gimp? Your help would be greatly appreciated. Thanks!

I would add guide to top of door, then add another guide at how every many pixels downward from the other guide that you want the number of pixels to represent. Then scale your image to that. so that the door fits between the guides.

Believe me, you do not want to do this. Gimp is a bitmap editorwhere the units are pixels and "real world" sizes depend on the image print resolution.

However:



(1) For any image you can change the units used down at the bottom of the window. It does not make any difference but I recommend inches.
(2) The measure tool will now use inches
(3) Measuring the door, for this image gives 17.11 inches.
(4) Image -> Scale Image brings up the scale dialogue and change the units to percentage.
Get your calculator out and for this image and a 68" high door, the scaling factor is 68 / 17.11 x 100 = 397 %
(5) Use that 397% for scaling the image

This is where you will run into problems, image file size.



(6) These are only warnings, you can still scale, but it takes time.
(7) Check the size on the scaled image.
Note: anything you copy/paste into the image has to be the same resolution as the image.

Thanks guys for helping this newbie out.

@trandoductin, thanks for the idea, I'll have to try that.

@rich2005, I appreciate you taking the time to map this out for me, that really helps. I can see why "I might not want to do this" now. The end result after getting both photos in the right position is to print out an 8.5x11 to show my wife. After scaling it up, I go to print and hit the Image Settings Tab I see the thumbnail and it looks and acts like the original pre-scaled version. So I'm guessing printing it at 8.5x11 wouldn't be an issue then?

I would use Inkscape and trace bitmap both images into paths. Then just play with the path nodes to fit the decor. Then you can scale the vector any size you need.

@Rod Thanks for the info, I'll take a look at Inkscape.

Oh don't forget to print out 8.5x11 isn't exactly 8.5x11. I know when I printed out some plaid patterns on 8.5x11 there's a thin margin if you want want exact you might have to print out 8x11 then measure what it actually is then do reverse calculations to get so that it's 1 to 1.

@trandoductin Thanks for the tip!