Interlace and P-Scan

Interlace

I did something silly by looking for the word “interlace” in the WordWeb dictionary. It displayed the meaning of interlocking together or twisting to form a bond. However, Interlace in the video quality consortium refers to the twisting of the overall image from the top left side to the bottom right side to form an image on the odd-lined basis. This step is repeated for the same direction but on even-lined basis to complete the whole picture. The Interlace system is implemented in our traditional CRT (Cathode Ray Tube) TVs which works on the frequency of 50 Hertz ( Frequency means the total cycle per second). To calculate the time required per cycle we can use the F = 1/T formula where F stands for frequency and T is the seconds required. So, the interlacing method was invented in decades ago in order to enhance the picture quality of the movie formats without consuming much bandwidth. With more bandwidth spared, the TV can be connected to other electrical devices such as the VCR, VCD and LD players without having loss of image signal. Due to the time required for the interlacing to carry out the whole action by displaying the picture from the top left to the bottom right, flickers and twisting occurs. Flickers means the “hiss hiss” sound and sharp noise generated on the image quality. As a result, rectangular-shaped or dotted lines might appear on the TV screen if you examine carefully towards it and you might as well observe rough scan lines on the frame.

Progressive Scan (P – Scan)

In the Progressive Scan (I will refer it as P-S for easy navigation), the process that completes the entire picture is exactly as same as Interlace mode, but differ in terms of the speed and simultaneous framing. For this time, the P-S will lock the whole picture from the top left to the bottom right both on even and odd line frames at the same time. The job was executed simultaneously so that the flicker will never appear on the TV screen. To perform this task, our TVs at home must have the function of 100 Hertz picture enhancement function as the higher the frequency, less probability that the flicker will actually take place. If we apply the same formula of F = 1/T at this time, we will get a twice lower in seconds. This means that the machine is successfully producing a lower response time of image. Response time is the key advantage in P-S especially we are viewing an object in motion. For instance, when the gunman fired a bullet or when the football was projected hastily, we might not be able to see the object clearly on normal 50 Hertz Interlaced CRT TVs as there are still flickers and pixels break-up (“Pau Kak” in Chinese). In the P-Scan, the picture quality is smoothened and thus providing a non-flicker frame. This means, the P-S can come up with a more detailed picture clarity compared to the Interlace even though they are both benchmarked using the video clip with the same resolution. The other advantage of P-S it the capability of activating the anti-aliasing function on the video. We usually heard about the anti-aliasing thingy in our computer 3D card but not knowing how it actually works. I was also uncertain about the anti-aliasing technology in the past when I was playing some 3D games but I only realized that putting the anti-aliasing to 0 or x2 will help to make the game less laggy compared to x4 and x8. Anti-aliasing is also known as intentional blurring which is invented to reduce the twitter effect on the graphic material. So, by putting up the best filter effect on the video, the image quality can be improved by reducing the flickering effect. Furthermore, with the P-Scan support on our TVs, we can watch our favourite DVD collections up to 480p quality. 480 means (640x480 Progressive Scan). With the additional Progressive Scan-ready DVD players, we can actually watch our DVD movies with high detailed image quality and also more crisp picture. Even though we are watching DVD5 (Single-layered DVD), we can still have the image quality upscaled to reach 480p. Once again, I am not saying that we can gain the HD format of the particular DVD title, but we can still see improvements on the show. And of course, if we insert a DVD9 (Double-layered DVD), we can experience the ultimate picture clarity of 480p.

DVD5 and DVD9

Please notice:- DVD5 and DVD9 are different not only in terms of cost and the storage capacity, but there more differences behind the scenes. In DVD5 we only enjoy the movie which consumed up to 4.7 GB whereas in DVD9 we got to savour the superior image quality of 8.5GB with more crystal-clear TruSurround sound mode. Plus, we can also notice there is a huge difference that lies in the DVD movie menu where in DVD9 the JAVA applications are more mature and realistic that offers greater satisfaction to the viewer. Moreover, DVD9 provides more menu features including extra commentary of the movie, trailers, the making of, games and wallpapers too. With the higher capacity of 8.5GB the movie is less compressed and the compression theory is also same when we are converting a Wav. File into a MP3 format.