Shrink Image without Loss of Quality

[messyj232]

Hi everyone! I have a pretty big image (it's a logo) and its dimensions are 6900x2500. I am trying to shrink it down to a width of about 500 but it always comes out pixelated. Is there anyway to shrink this image without losing quality? Thank you very much!

[Ofnuts]

This is due to spatial frequency folding. The cure is to blur the image before you scale down, to remove the details that would be frequency-folded but wouldn't be visible in the scaled-down image anyway. Blur how much, you will ask... by the scaling ratio: 6900/500 in your case. You don't even need to compute this on the side, open Filter>Blur>Gaussian blue and enter 6900/500 in the Blur radius fields (should yield 13.8).

Unblurred:

   

Blurred:

   

This said, this logo likely exists as a vector image (.ai, .svg) and scaling it as a vector image (Inkscape, Illustrator) would yield perfect results.

[rich2005]

Yeah, as a SVG. Partly redrawn, partly converted from the bitmap. If I could find the fonts easily, I would have replaced the text as well.

The horizontal white stripes suffer when downscaling so made them a little wider and moved a little.

Open an svg in Gimp like this:



and I would keep the depth to 200 pix if possible. Smaller and you will have to repaint those white lines.

   

[messyj232]

Ofnuts, thank you very much!!!

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Rich 2005, thank you! Great response, I really appreciate it. Especially because I couldn't find anything online or in the forums!