Resizing question

[Tony81]

Hello, I was wondering if resizing a video from 640x480 to 320x240 would result in data loss? There are 480 interlaced lines to the picture, if the video is resized to 240, does that mean 240 lines are taken out? Or is it just compressed with 480 lines still intact?

[jggimi]

Hello, Tony81, welcome to Doom9's forum!

I'll try to answer your question, which is fairly generic as it doesn't relate to any particular process. If you want a better answer, you'll have to describe what you want to accomplish.

A "pixel" is a single dot of color, and the smallest speck of information in a digital picture. A single frame of video at 640x480 has 307,200 pixels. A single frame of video at 320x240 has 76,800 pixels, one quarter of the pixels in the larger image. There is less information in the smaller image, which is intentional data loss. There's no "squeeze" of the visual information ... there are merely less pixels in the smaller image.

There are several different methodologies for removing pixels when resizing, that can impact how your eye and brain decipher the smaller image, with names such as "bilinear" and "bicubic." When the person doing the resizing has a choice, he or she chooses based upon what looks best to them for the task at hand.

[Tony81]

Hi jggimi, I'm happy to join doom9!

Thanks for the explanation. If I'm capturing to 640x480, all 480 interlaced lines of resolution are captured. But if I'm capturing or resizing down to 320x240, does that mean only half the lines (240) of resolution are kept?

[trevlac]

Originally posted by Tony81
But if I'm capturing or resizing down to 320x240, does that mean only half the lines (240) of resolution are kept?
For capturing, yes. Half the lines are thrown away. For resize, it probably depends on the resize method as to what data is lost. But data is lost. :(