How does downscaling work? - Blu-ray Forum

hendra · 01-02-2009, 11:33 PM

Take a 1920x1080 jpeg file, shrink it so that it will fit with your monitor that has less than 1920x1080 native resolution. The jpeg picture will have jaggies. But take a BD 1080p movie and feed it to a monitor that has less than 1920x1080 native resolution, the picture will still look perfect with no visible jaggies. I don't notice any jaggies with my 1600x900 16.4" laptop monitor.

What is the secret? What is the difference between shrinking a jpeg picture and downscaling a BD movie?

RazorFromHRSnet · 01-03-2009, 03:32 PM

when you shrink your JPEG's are you using a good program like photoshop to do it? or are you just zooming in and out with the magnifying glass tool? (I find magnifying glass doesnt always look as good as really doing the processing to shrink the file.)

I'd say the man reason you don't notice is cause the image is in motion.

Personally, I never notice jaggies when downscaling, only upscaling.

Certain scaling algorityhims just remove lines (if you were making it 10% smaller, it would remove every 10th line for example, 25% every 4th line), others do more detailed analysis to preserve details.

01-02-2009, 11:33 PM	#1
hendra Active Member Member since:Dec 2007	How does downscaling work? Take a 1920x1080 jpeg file, shrink it so that it will fit with your monitor that has less than 1920x1080 native resolution. The jpeg picture will have jaggies. But take a BD 1080p movie and feed it to a monitor that has less than 1920x1080 native resolution, the picture will still look perfect with no visible jaggies. I don't notice any jaggies with my 1600x900 16.4" laptop monitor. What is the secret? What is the difference between shrinking a jpeg picture and downscaling a BD movie?

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01-03-2009, 03:32 PM	#2
RazorFromHRSnet Active Member Member since:Mar 2008 Blu-ray collection:89 Blu-ray reviews:1	when you shrink your JPEG's are you using a good program like photoshop to do it? or are you just zooming in and out with the magnifying glass tool? (I find magnifying glass doesnt always look as good as really doing the processing to shrink the file.) I'd say the man reason you don't notice is cause the image is in motion. Personally, I never notice jaggies when downscaling, only upscaling. Certain scaling algorityhims just remove lines (if you were making it 10% smaller, it would remove every 10th line for example, 25% every 4th line), others do more detailed analysis to preserve details.

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