Re: Avoiding pirating of DVD images

Today, John McWilliams made these interesting comments ...

So why do the JPEG and TIFF standards use DPI as the measure
of horizontal and vertical pixel density in digital images ?

12 years ago, yeah. Today, there's more sophistication, and
many folks know the difference between pixels and dots. DPI is
connected with scanning and printing. Pixels are associated
with digital capture and processing on computers.

Precisely. And, since the photogs got together with the
mathematicians to create JPEG, they tried to approximate the file
size reduction of about 50% of a TIFF with LZW compression for
JPEG=1. And, JPEG uses a unitless 1-100 scale, although several
popular apps including PS and Irfanview choose to call it a
percentage compression because kids get taught in junior high that
anything that is 0-100 or 1-100 must be a percentage. But, anyone
with an ounce of brains and a 4-function calculator can quickly
figure out that JPEG compression is neither a percentage nor is it
linear.

--
HP, aka Jerry

Member, Chrysler Employee Motorsport Association (CEMA)
http://www.cemaclub.org/default.html
.

Relevant Pages

  • Re: 4mp doubled = 16mp!?
    ... quality JPEG settings did indeed make more detailed images ... my 2 Kodaks have no ability whatsoever to alter compression, ... large prints from as large an image in mega pixels as you can ...
    (rec.photo.digital)
  • Re: Sharpness in Tiff Scans
    ... Tiff vs. JPEG has nothing to do with resolution (number of pixels). ... Nor, necessarily, with sharpness as long as you don't get carried away in the degree of compression in the JPEG format. ...
    (comp.periphs.scanners)
  • Re: JPG compression - yet another question !
    ... That is 4,915,200 pixels which would be about 15MB for the in- ... the space besides just the pixels, the header info, and EXIF. ... However, once JPEG does it's magic, all bets are off. ... that it just isn't possible to recover the compression factor ...
    (rec.photo.digital)
  • Re: JPG compression - yet another question !
    ... That is 4,915,200 pixels which would be about 15MB for the in- ... the space besides just the pixels, the header info, and EXIF. ... However, once JPEG does it's magic, all bets are off. ... that it just isn't possible to recover the compression factor ...
    (rec.photo.digital)
  • Re: ADPCM question
    ... then again, IMO, not even JPEG is perceptually lossless. ... difference is clear (file gets larger, but quality does not). ... I suspect most people can't normally see individual pixels at ... light and dark, a subtle throbbing of momentary yet solid-seeming light over ...
    (comp.compression)