From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <6e35c0620604271226o17e6cccdm63a0794e550a39b4@mail.gmail.com> Date: Thu, 27 Apr 2006 12:26:12 -0700 From: "Jack Johnson" To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu> Subject: Re: [9fans] PNG and APE (cntd) In-Reply-To: <6ac270891b09f4b5e1ea25ce1ab1adc5@terzarima.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <6ac270891b09f4b5e1ea25ce1ab1adc5@terzarima.net> Topicbox-Message-UUID: 4897f816-ead1-11e9-9d60-3106f5b1d025 On 4/27/06, Charles Forsyth wrote: > > And, BTW, PNG allows 16-bit per colour, a 48-bit depth per pixel. > > Thanks to libpng, my "npng" can render these as 24-bit images. > > ``the human ear can't hear as high as that / still, it ought to please an= y passing bat'' I used to do some image fiddling a long time ago (image prep -> TGA for television), and came across some info regarding medical x-ray photographs being stored in a 12-bit grayscale format. It's likely that so fine a variation is either above or right on the edge of human perception (given current working environments), but one counterargument is that maybe it's not a human looking at the data. Plus, I think 12 bits per color would be right around the limit of film, something like a 4000:1 contrast ratio, so depending on the scanner you'd likely be pushing the limits of the original medium anyway, "lossless" transfer from analog to digital, whether or not you're in a good position to make use of the data. Archaeologists have the same problem all the time, looking at data gathered by previous scientists and realizing the original gatherers didn't save enough information for the current questions, so now they tend to swing the opposite direction and record all the minutiae so that years later someone can glean new information from an old dig. One day, you may be a bat. -Jack