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Article View: sci.image.processing
Article #865

Question: Converting a Negative to a Positive

#865
From: Local Brian Lee
Date: Mon, 23 Nov 1992 23:22
51 lines
2343 bytes
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hello people,

I'm not too sure if this is the right place to ask this but if it's
not I'm sure s/one will set me straight.

This is probably a simple question for all you graphics/imaging gurus
out there so I'm expecting a flood of responses:

OK:
If I have a 35mm negative and I grab that slide onto my PC with some
sort of frame grabber then what's involved in turning that image
into a positive ?

Is it a simple matter of subtracting every pixel from its max value ?

e.g. say I have a 24 plane image (i.e. no colour map) to get a positive
of a pixel with a value of say 0x123456 is it as simple as doing:

0xffffff - 0x123456 = positive value ?

Any comments please ...Thanks...Brian
hello people,

I'm not too sure if this is the right place to ask this but if it's
not I'm sure s/one will set me straight.

This is probably a simple question for all you graphics/imaging gurus
out there so I'm expecting a flood of responses:

OK:
If I have a 35mm negative and I grab that slide onto my PC with some
sort of frame grabber then what's involved in turning that image
into a positive ?

Is it a simple matter of subtracting every pixel from its max value ?

e.g. say I have a 24 plane image (i.e. no colour map) to get a positive
of a pixel with a value of say 0x123456 is it as simple as doing:

0xffffff - 0x123456 = positive value ?

Any comments please ...Thanks...Brian
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From: lee@bribie.sna.dec.com (Local Brian Lee)
Subject: Question: Converting a Negative to a Positive
Message-ID: <1992Nov23.232235.10201@funlwb.enet.dec.com>
Lines: 51
Sender: l_lee@bribie.sna.dec.com (Local Brian Lee)
Nntp-Posting-Host: bribie.sna.dec.com
Reply-To: lee@aussie.enet.dec.com
Organization: Digital CSS Sydney Australia
Date: Mon, 23 Nov 1992 23:22:35 GMT