Upscaling of SD1 images to 60 Mpix with example

xpatUSA wrote:

Scottelly wrote:

xpatUSA wrote:

Iconoscope wrote:

I upscale most images 200% prior to further post processing in order to have finer control of sharpening and noise reduction. This also provides smoother edges that otherwise may be plagued with 'jaggies'. Then finally rescale the image to the size I need for presentation. I use Adobe Photoshop CC almost exclusively for rescaling images.

I never re-sample images before post-processing and would not recommend it to anybody whose Editor is capable of zooming the review image, sorry.

An edge "plagued with jaggies" in my book is indicative of a well-focused shot provided it looks like this, according to Falk Lumo (@falconeyes here):

A perfect edge; anything more jaggy is over-sharpened, see link below

From Section 1.2.2 of:

http://www.falklumo.com/lumolabs/articles/sharpness/index.html

Re-sampling an image twice is anathema to me. Once is bad enough . . but twice !?

Please pardon the negative response!

I do understand the basis of your post, apropos of which you might find this of interest:

http://kronometric.org/phot/iq/Down%20sampling%20methods.htm

There, Bart van der Wolf says:

" . . try and reduce high spatial frequencies before we downsize. I'll demonstrate two simple methods that will catch most of the trouble. The first method is by pre-blurring the image, thus gradually removing more detail as the spatial frequency increases . . ."

Seems like your method is quite similar, albeit based on eye-balling rather than numbers.

What re-sampling algorithm do you use for the 200% upsize and what one(s) for downsizing?

I'm trying to figure out what exactly 200% means. Are we talking 15 MP to 30 MP or from 5,000 pixels across to 10,000 pixels across?

For me, Scott, the latter. That matches, for example, FastStone Viewer's re-sizing options. That is to say, if you select 200%, the pixel width box automatically doubles. If you enter double the pixel width instead, the percent box automatically shows 200%.

What does SPP do for double size? Does it double the MP?

It doubles the horizontal AND vertical resolution Ted, quadrupling the number of pixels, creating a big, blurry image with jagged edges, wherever there is a sharp, angled line in the image.

Of course that might be less of a problem, depending on the method of scaling.

Either way is going to cause problems.

How does either way cause problems, and what would those problems be?

It's going to slow down my computer Ted.

I'm not sure I see the point.

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