The above examples are NTSC. PAL DVDs have a 720x576 image, so the ratios are significantly different than shown above, but the principles are the same.
Video source (1.33)
A. Source material in 1.33 aspect. Typically shot with a video camera.
B. Image as stored on DVD. Notice that it is stretched horizontally slightly, since 720/480 is 1.5, not 1.33.
C. When displayed on a 1.33 TV, the image returns to its normal aspect (1.33). This is not accomplished by reducing the 720x480 image to 640x480 — rather, the 720 pixels of each row are simply transformed by the DVD player into an analog signal for the TV, which displays it at the appropriate width for its 1.33 screen.
D. When displayed on a 1.77 TV, the TV may be set to show the image with bars on the side, like this...
E. ...or to stretch the image to fill the whole 1.77 screen, like this.
Movie source (1.77)
F. Source material in 1.77 aspect. Typically shot with a movie camera (or a video camera in 16x9 mode).
G. Image as stored on DVD. Notice that it is squeezed horizontally — this is the “anamorphic widescreen” feature described on the package.
H. When displayed on a 1.33 TV, the image is letterboxed by the DVD player or TV. (In these illustrations, grey is used to indicate any blank areas created on-the-fly by the DVD player or TV. On your TV, the bars will be black, not grey.)
I. On a 1.77 TV, the image is stretched back to its normal appearance, and perfectly fills the TV screen.
Movie source (2.35)
J. Source material in 2.35 aspect. Typically shot with a movie camera using a special anamorphic lens that squeezes a 2.35 image into an ordinary, 35mm, 1.77-aspect movie film frame. The Star Wars and Matrix movies were shot this way, for example.
K. This is what the image actually looks like on the 35mm film. When played in the theater, a reversing lens stretches it back to the way it looks in illustration J.
L. Image as stored on DVD. This image does include some letterboxing. Note: Although they look similar, the degree of anamorphic squeezing in this image (L) is not the same as the amount in image K.
M. When displayed on a 1.33 TV, the image is additionally letterboxed by the DVD player or TV. (In these illustrations, grey is used to indicate any blank areas created on-the-fly by the DVD player or TV. On your TV, the bars will be black, not grey, so the letterboxing in the DVD’s image and the letterboxing generated by the DVD player or TV will appear to be one, big letterbox.)
N. On a 1.77 TV, the image is stretched back to its normal appearance, and perfectly fills the TV screen. The letterboxing in the image is, of course, apparent.
