Standard DVD players can show JPG image files from a regular data CDR disk. See your DVD player's manual about showing JPG images, for the media disk types it will play, and how many JPG files it will show. The DVD player will show any size of JPG image given to it, but it can only output the standard TV signal, so it must resample too-large images to the correct size, which can play sluggishly.
Blue Ray and HD DVD players and recorders exist now. I have not seen one, sorry, but I suppose those HD players will play HD-size JPG files too? 1280x720 or 1920x1024 pixel image size fits the HD screen size of course. Which seems obvious, and the rest this page is instead about standard DVD players.
Until HDTV, North American standard television screens (called NTSC for National Television System Committee) are drawn with 525 horizontal scan lines, 480 of which are visible on the screen (the remaining lines are blanked out to hide the duration of the beam retrace back to the top of the screen). It simply doesn't matter if the TV screen size is 12 inches or 60 inches, the number of picture lines is always the same.
NTSC television is analog (before HDTV), but these 480 lines are correctly matched digitally by 480 pixels vertically. More cannot help. The TV aspect ratio (shape) is 4:3, so it is matched by 480 x 4/3 = 640 pixels horizontally. This is also the origin of the computer VGA 640x480 pixel screen size.
Europe, Australia, and much of the rest of the world use PAL television systems (French SECAM is essentially the same) with a higher resolution of 625 lines, with 576 lines being visible, so the 4:3 number is 768x576 pixels for PAL systems. PAL users should always substitute their own 768x576 numbers here.
You could make your JPG images be 1280x720 pixels now, ready for a HD DVD player, but today, that will show 16:9 and operate slower. Or you could just plan to rerun the resample batch again then, to recreate the right size image when the time comes.
For standard DVD players (not HD), the "correct" image size is 640x480 pixels (disputed in the next paragraph). The idea is to make your image size fit within 640x480 pixels for the television screen. Regardless of your TV type or size, this is all the standard DVD player can do. Those are the maximum useful dimensions for standard DVD players, which must resample any larger image to this smaller size.
That is the theory, but in practice, the standard television sets intentionally show an oversize image, extending the image offscreen at the sides, called overscanning (to be sure we never see the edges). The television show creators know not to put anything important near the side edges, because it will be cut off there. The image is about 10% larger than the physical screen will show. To us, it means we can't show a full 640 pixel image width. We can only see about 90% of that width, which you may want to take into account for photos. 90% of 640 is 576 pixels. Overscan varies with TV sets, it won't be exact, you may want to experiment. To see all of the image, my own preference is to keep the image within 576x480 pixels (just my opinion). This is 6:5 aspect ratio.
If you want to show your entire uncropped image, then make it 576 pixels wide, and let the height float smaller, like 576x383 for 3:2 images - it will view with a black border at top and bottom. Or make tall images be full 480 pixels height, and let the width float smaller, like 319x480 pixels for 3:2 images, with the black border at the sides. Irfanview batch and Photoshop menu File - Automate - Fit Image offer this automated resampling decision regardless of image orientation. However the image can view considerably larger if you can crop the excessive long ends first.
If you want images to fill the full screen (without any black edges), you must crop landscapes to the 4:3 or 6:5 shape (see how here, but this cropping for full screen is optional). Then resample them to 480 pixels height (bicubic) but don't allow more than the maximum width. The image dimensions should fit within the full 640x480 or the reduced 576x480 size you choose (if NTSC, or for PAL, the full 768x576 or a reduced 691x576 pixels).
After resampling, then sharpen modestly (USM 0.8 Radius for video), and save as JPG Quality 9 (High Quality). Save this as a copy, don't ever overwrite your larger archived master file.
Many people use fancy video software like Adobe Premiere to create "movie" DVDs, with sound and motion. The television screens are still the same size, but the trend today is to use large still images, a few megapixels, to allow zooming and panning in Ken Burns style. The software will resample to output the correct size smaller screen image for each frame. That subject is "video", not scanning, and I can't help with that. Read your manuals, and maybe see www.videohelp.com.
Copyright © 2007 by Wayne Fulton - All rights are reserved.
