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blurry images after scaling down

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blurry images after scaling down ChadDavis 28 Nov 00:34
  blurry images after scaling down David Gowers 28 Nov 06:35
ChadDavis
2007-11-28 00:34:40 UTC (over 6 years ago)

blurry images after scaling down

I'm down scaling some tif images. These images are created with a graphics software for making diagrams and the like. Geometric shapes and text mostly. When I open the tif in Gimp they are perfectly crisp. When I scale the image down in size, it becomes slightly blurry, even when opting for the "best" cubic algorithm.

Is this to be expected? What's the best practice for preparing graphics so that they are crisp? I thought i should make them large and that way they would have extra resolution. But apparently scaling down is a lossy practice?

Thanks,
Chad

David Gowers
2007-11-28 06:35:25 UTC (over 6 years ago)

blurry images after scaling down

Hi Chad,

On Nov 28, 2007 10:04 AM, ChadDavis wrote:

I'm down scaling some tif images. These images are created with a graphics software for making diagrams and the like. Geometric shapes and text mostly. When I open the tif in Gimp they are perfectly crisp. When I scale the image down in size, it becomes slightly blurry, even when opting for the "best" cubic algorithm.

Is this to be expected?

Yes, Gimp deals with pixels, not vectors. when you scale down, you reduce the number of pixels that are used to represent the image.

If your graphics are vector based and you want to keep them that way, use a vector drawing program like Inkscape to manipulate them, not a raster manipulation program like GIMP.

What's the best practice for preparing graphics so that they are crisp? I thought i should make them large and that way they would have extra resolution. But apparently scaling down is a lossy practice?

Extra precision just means a more accurate averaging. Say you are scaling the image down to 50% of original size.. that means that each resultant pixel is calculated from the average of a 2x2 square of pixels. say that 2 of these input pixels are black, and two are white, since it is an average, each of the following produce the same result:

BW BW

WB
BW

WB
WB

WW
BB

So, it is indeed lossy.

If you want a raster image to be maximally crisp, your best bet is to draw it at the final size. If you want a vector image to be crisp, your work is probably unrelated to the GIMP.