How to increase image resolution?
I need to obtain a print quality image from an existing image. The image dimensions are 1024 x 768 pixels, and the print size is 12 inches x 8 inches.
The current resolution is 64 x 64 pixels per inch (ppi).
The menu options Image | Print Size | X resolution and Image | Print Size | Y resolution allow me to change the ppi setting.
When I change the ppi to 300 x 300, the print size of the image shrinks to 3.4 x 2.5 inches. I want to keep this at 12 x 8 inches.
How can I keep the same print size (inches) but a higher ppi?
I am assuming you mean the current DPI is 64ppi x 64 ppi. You want GIMP to add pixels to the 1024x768 image without changing the size in inches. The only way I know to do this is in two steps, both of which use Image | Scale Image.
In Image | Scale Image, set Interpolation to None and change the X and Y resolution. You will see that the Image Size in pixels doesn't change. Hit Scale, and the image will have the new resolution.
Go back into Image | Scale Image. Set Interpolation to Cubic. This time, change the Image Size to be what you want in inches or cm. GIMP will compute the resulting pixel resolution and resample the image.
This way you don't have to manually convert between inches, dpi, and pixels. Hope this helps!