Panasonic AG-DVX200 Tech Brief - Volume 1 - Page 3

HD streaming, it opened new markets for remastered high-definition versions -- which created new opportunities and new revenue streams for those producers. Unfortunately for those who shot their projects on standard-definition TV cameras, there is no higher-definition master footage to go back to. Accordingly, while you may not necessarily see a need or even an opportunity to deliver a 4K or UHD version of your projects, wouldn't it be nice to have the higher-resolution master copies of the footage to go back to in case such an opportunity were to arise? Sharper HD Footage: When you have a much larger source image to work from, shrinking it down to HD size can make for the sharpest, clearest HD images possible. A super-sampled ultra-high-definition image, when resized down to HD frame sizes, can result in images that hold as much detail as the HD frame size is capable of retaining. This means that it is possible to get sharper HD images from a 4K/UHD camera, by resizing the images in post, than you would get from even a very high-performance HD camera. Reduced Noise: Another benefit to downconverting 4K/UHD footage to HD in post production is that you'll see a significant reduction in visible noise in the image. When converting UHD/4K footage down into 1080p footage, each 2x2 group of UHD pixels are used to create a single pixel in HD. Combining the 2x2 group of UHD pixels can result in "averaging" the noise from each pixel together, resulting in smoothing out the noise and greatly reducing its visibility. Increased Color Resolution And Bit Depth: One excellent benefit of downconverting UHD/4K footage to 1080 HD in post is that you can realize an increase in proportional color resolution and a notable increase in bit depth. The AG-DVX200 records 4K or UHD footage at 8 bits per pixel and utilizes 4:2:0 color sampling. After downconversion, the resulting footage has 10 bits per pixel and 4:4:4 color sampling! Yes, you can convert 3840x2160 8-bit 4:2:0 recorded footage into 1920x1080 10-bit 4:4:4 footage in post. To understand the color sampling advantage, you'd have to first understand that the camera records its footage in 4:2:0 color sampling. That means (simply put) that there is one color sample for every 2x2 block of pixels. In any given 2x2 block of pixels there are four different "brightness" samples, but they all share one "color" sample. Effectively, within the 3840 x 2160 frame, there is a 1920 x 1080 matrix of color samples, one for every 2x2 block of pixels. During the downconversion to HD, each block of 2x2 brightness samples are converted into one HD pixel, creating a 1920 x 1080 matrix of brightness pixels. This 1920 x 1080 "brightness" (luminance) matrix can be effectively married to the originally-recorded 1920 x 1080 "color" matrix, resulting in one individual and unique color sample for each and every brightness pixel. The result is 4:4:4 color sampling at high-definition resolution. In terms of pixel depth, the original recorded footage is quantized and recorded at an 8-bit depth, providing for up to 256 shades per pixel. Other formats, like Panasonic's own AVC-Intra, quantizes and records at a 10-bit depth, for up to 1,024 shades per pixel. Having deeper bit depth provides the ability for finer shading and more subtle transitions, especially apparent on smooth gradients (such as in a clear blue sky). Generally 8-bit cameras perform fine for most