Hi Bruce, As I understand it, the basis for colour management - the CIE color space - was produced after extensive studies of the human visual system. Without going into a depth (there is a very full definition available on Wikipedia - search both "Color vision" and "CIE 1931 Color Space") and with respect to your experience in this field, I feel that is putting the cart a little before the horse. It's no coincidence that computer graphics standards have striven for and now essentially settled on a 24 bit colour space. It is because it is possible to represent the CIE (or all other) color spaces within the color cube defined by 256x256x256 values and, in a sense, this color space represents a model of everything that we can see. I know that this is in a sense a subjective statement since perception is in part a pyschological phenomenon - look at things like color constancy as an example - a camera will record the light density changes across a wall, while our eye/brain system will often simply see a white (or other colour) surface (unless we know about colour constancy and look again). So the very establishment of an international colour standard was in one sense an attempt to quantify the human visual system which is an attempt that can only approach the visual system. So I regard our attempts to produce some sort of 'definitive' and all encompassing reproduction system to be doomed to failure - largely because what we think we see depends a lot on contextual information and not some kind of application to a number of 'levels'. Please feel free to correct me if I'm going off at a tangent here but I feel that a lot of this talk about bit depths and image size is about a pursuit of a technical excellence that begins to depart from the actual process of vision. -- Alan Ansell aansell@... ----- Original message ----- From: "Bruce Watson" <bwyg@...> To: DigitalBlackandWhiteThePrint@yahoogroups.com Date: Tue, 10 Apr 2007 12:52:34 -0400 Subject: Re: [Digital BW] Re: 8bit to 16 bit Alan Ansell wrote: > ...the human visual system can only see roughly the eqiuvalent of the 16.7 million colours produced by 256³ (3 x the 8-bit channels), ... > What makes you think that? We use eight bits per channel (RGB) because it fits the (current) computer architecture (and makes a smaller memory footprint and smaller files), not because it's a good fit with human perception. A closer fit to human visual capability would be around 14 bits per channel. Some studies apparently have shown that you need a full 16 bits per channel, while some showed you could get by with as little as 12 bits per channel. In fact, the resolution you need is not the same with each channel -- you need more with green than you do with red or blue. But from a computer standpoint, you need either eight or 16 bits per channel, so if you want to capture it all, you need 16 bits per channel. If you want to learn more about human perception with the emphasis on art, try "Vision and Art: The Biology of Seeing" by Margaret Livingstone. I highly recommend it. -- Bruce Watson References 1. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/message/84771;_ylc=X3oDMTM2djNnZDVpBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBG1zZ0lkAzg0ODIzBHNlYwNmdHIEc2xrA3Z0cGMEc3RpbWUDMTE3NjIzNzU5NQR0cGNJZAM4NDc3MQ-- 2. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/post;_ylc=X3oDMTJxMHMwMzYyBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBG1zZ0lkAzg0ODIzBHNlYwNmdHIEc2xrA3JwbHkEc3RpbWUDMTE3NjIzNzU5NQ--?act=reply&messageNum=84823 3. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/post;_ylc=X3oDMTJlamx2dnVnBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwNmdHIEc2xrA250cGMEc3RpbWUDMTE3NjIzNzU5NQ-- 4. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/messages;_ylc=X3oDMTJlcjY1MWFiBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwNmdHIEc2xrA21zZ3MEc3RpbWUDMTE3NjIzNzU5NQ-- 5. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint 6. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/ 7. http://groups.yahoo.com/;_ylc=X3oDMTJkaXBndmxqBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwNmdHIEc2xrA2dmcARzdGltZQMxMTc2MjM3NTk1 8. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/join;_ylc=X3oDMTJmNHVoZ3VqBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwNmdHIEc2xrA3N0bmdzBHN0aW1lAzExNzYyMzc1OTU- 9. mailto:DigitalBlackandWhiteThePrint-digest@yahoogroups.com?subject=Email%20Delivery:%20Digest 10. mailto:DigitalBlackandWhiteThePrint-traditional@yahoogroups.com?subject=Change%20Delivery%20Format:%20Traditional 11. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint;_ylc=X3oDMTJkbG41ZXQ2BF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwNmdHIEc2xrA2hwZgRzdGltZQMxMTc2MjM3NTk1 12. http://docs.yahoo.com/info/terms/ 13. mailto:DigitalBlackandWhiteThePrint-unsubscribe@yahoogroups.com?subject= 14. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/members;_ylc=X3oDMTJmMmg3bjM3BF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwN2dGwEc2xrA3ZtYnJzBHN0aW1lAzExNzYyMzc1OTU- 15. http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint;_ylc=X3oDMTJlY2NqbGpjBF9TAzk3MzU5NzE0BGdycElkAzM3MDIzMTEEZ3Jwc3BJZAMxNzA1MDE5MTgyBHNlYwN2dGwEc2xrA3ZnaHAEc3RpbWUDMTE3NjIzNzU5NQ-- 16. http://groups.yahoo.com/gads;_ylc=X3oDMTJjMzhhamY0BF9TAzk3MzU5NzE0BF9wAzEEZ3JwSWQDMzcwMjMxMQRncnBzcElkAzE3MDUwMTkxODIEc2VjA3NsbW9kBHN0aW1lAzExNzYyMzc1OTU-?t=ms&k=Fine+art+photography&w1=Fine+art+photography&w2=Digital+photography&w3=Digital+photography+print&w4=Digital+photography+technique&w5=Fine+art+photography+print&c=5&s=149&g=2&.sig=AhyJLEY_mHSSQCNHMyZ1HQ 17. http://groups.yahoo.com/gads;_ylc=X3oDMTJjbnVodXMyBF9TAzk3MzU5NzE0BF9wAzIEZ3JwSWQDMzcwMjMxMQRncnBzcElkAzE3MDUwMTkxODIEc2VjA3NsbW9kBHN0aW1lAzExNzYyMzc1OTU-?t=ms&k=Digital+photography&w1=Fine+art+photography&w2=Digital+photography&w3=Digital+photography+print&w4=Digital+photography+technique&w5=Fine+art+photography+print&c=5&s=149&g=2&.sig=SvQKuVtg6IzggzvbNW76cQ 18. http://groups.yahoo.com/gads;_ylc=X3oDMTJjOGJwc2t0BF9TAzk3MzU5NzE0BF9wAzMEZ3JwSWQDMzcwMjMxMQRncnBzcElkAzE3MDUwMTkxODIEc2VjA3NsbW9kBHN0aW1lAzExNzYyMzc1OTU-?t=ms&k=Digital+photography+print&w1=Fine+art+photography&w2=Digital+photography&w3=Digital+photography+print&w4=Digital+photography+technique&w5=Fine+art+photography+print&c=5&s=149&g=2&.sig=g1PLpDs3VAJRCiHquYf9Kw 19. http://groups.yahoo.com/gads;_ylc=X3oDMTJjaTBxcHBzBF9TAzk3MzU5NzE0BF9wAzQEZ3JwSWQDMzcwMjMxMQRncnBzcElkAzE3MDUwMTkxODIEc2VjA3NsbW9kBHN0aW1lAzExNzYyMzc1OTU-?t=ms&k=Digital+photography+technique&w1=Fine+art+photography&w2=Digital+photography&w3=Digital+photography+print&w4=Digital+photography+technique&w5=Fine+art+photography+print&c=5&s=149&g=2&.sig=z42wd62NioHid6gdeL6dXQ 20. http://groups.yahoo.com/gads;_ylc=X3oDMTJjZDNlOHM5BF9TAzk3MzU5NzE0BF9wAzUEZ3JwSWQDMzcwMjMxMQRncnBzcElkAzE3MDUwMTkxODIEc2VjA3NsbW9kBHN0aW1lAzExNzYyMzc1OTU-?t=ms&k=Fine+art+photography+print&w1=Fine+art+photography&w2=Digital+photography&w3=Digital+photography+print&w4=Digital+photography+technique&w5=Fine+art+photography+print&c=5&s=149&g=2&.sig=a-SzixGQMrtqCBQRWDYQjw 21. http://us.ard.yahoo.com/SIG=12i7uri5t/M=493064.9803190.10510181.8674578/D=groups/S=1705019182:NC/Y=YAHOO/EXP=1176244795/A=3848606/R=0/SIG=12t5n1ri6/*http://news.yahoo.com/i/721;_ylt=A9FJqZeOvK5EKmgAbwsLMxIF;_ylu=X3oDMTA2NWJlcmlsBHNlYwN0bg-- 22. http://us.ard.yahoo.com/SIG=12jp92d1l/M=493064.10512181.11138666.8674578/D=groups/S=1705019182:NC/Y=YAHOO/EXP=1176244795/A=4507179/R=0/SIG=12de4rskk/*http://us.rd.yahoo.com/evt=50284/*http://finance.yahoo.com/personal-finance 23. http://us.ard.yahoo.com/SIG=12i0rmfo0/M=493064.9803235.10510228.8674578/D=groups/S=1705019182:NC/Y=YAHOO/EXP=1176244795/A=4299916/R=0/SIG=112p3i6po/*http://games.tv.yahoo.com/trump/ [Non-text portions of this message have been removed]
Message
Re: [Digital BW] Re: 8bit to 16 bit
2007-04-10 by Alan Ansell