The aspect ratio of an image is its width divided by its height.

The following table illustrates the common aspect ratios presented on DVD along with the total active pixels presented in each possible DVD format. I have highlighted the best formats in green.

Aspect Ratio
4x3 PAL
16x9 enhanced PAL
4x3 NTSC
16x9 enhanced NTSC
1.33:1
720 x 576 = 414,720
538 x 576 = 309,888
720 x 480 = 345,600
538 x 480 = 258,240
1.66:1
720 x 461 = 331,920
671 x 576 = 386,496
720 x 384 = 276,480
671 x 480 = 322,080
1.78:1
720 x 430 = 309,600
720 x 576 = 414,720
720 x 358 = 257,760
720 x 480 = 345,600
1.85:1
720 x 414 = 298,080
720 x 554 = 398,880
720 x 345 = 248,400
720 x 461 = 331,920
2.35:1
720 x 326 = 234,720
720 x 436 = 313,920
720 x 271 = 195,120
720 x 363 = 261,360

 

References: