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09/18/2004 07:58:17 AM · #1 |
Am doing a second pass of the smoke challenge and trying to comment on at least 50 of them, here is my issue...
Several photos have been bumped up after I download the image and lightened them (image/adjustments/shadow highlight) so I can see what is going on (my monitor is very dark and will be replaced soon).
This is the strange bit, I just had a thought that if I need to brighten the images I can't see well then surely a 'similar' image (swirling smoke) that I can see well and scored highly would become over exposed when I used the same method of lightening in CS?
Not so, my favourite image just got sharper when I did it and not blown at all. Is this because the images I see well already are actually better taken shots? plus I am worried that I may change the fotogs desired result by changing the light to compensate for my bad monitor and in order to stay consistent I guess I need to make the same change to all pictures?
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09/18/2004 09:00:10 AM · #2 |
It may be better for you to wait untill you have the new monitor for you to vote with confidence.
I don't think with what you need to do to a photo you can accuratly see what has been attempted by the photographer.
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09/18/2004 09:07:19 AM · #3 |
Originally posted by Gurilla:
It may be better for you to wait untill you have the new monitor for you to vote with confidence.
I don't think with what you need to do to a photo you can accuratly see what has been attempted by the photographer. |
Yes, and a good excuse for taking a break from commenting for a while. Maybe with a new monitor I'll be able to submit better pictures of my own as well (or at least see what eveybody else does).
I'm still drawn between LCD and CRT, there are pros and cons with both, space may be the deciding factor (tho anything will be better right now)
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09/18/2004 10:09:25 AM · #4 |
Originally posted by Ecce Signum:
Originally posted by Gurilla:
It may be better for you to wait untill you have the new monitor for you to vote with confidence.
I don't think with what you need to do to a photo you can accuratly see what has been attempted by the photographer. |
Yes, and a good excuse for taking a break from commenting for a while. Maybe with a new monitor I'll be able to submit better pictures of my own as well (or at least see what eveybody else does).
Thinking about LCD myself as they look great! BUT not sure how they calibrate for photo work.
I'm still drawn between LCD and CRT, there are pros and cons with both, space may be the deciding factor (tho anything will be better right now) |
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09/18/2004 02:45:13 PM · #5 |
Originally posted by Ecce Signum:
Am doing a second pass of the smoke challenge and trying to comment on at least 50 of them, here is my issue...
Several photos have been bumped up after I download the image and lightened them (image/adjustments/shadow highlight) so I can see what is going on (my monitor is very dark and will be replaced soon).
This is the strange bit, I just had a thought that if I need to brighten the images I can't see well then surely a 'similar' image (swirling smoke) that I can see well and scored highly would become over exposed when I used the same method of lightening in CS?
Not so, my favourite image just got sharper when I did it and not blown at all. Is this because the images I see well already are actually better taken shots? plus I am worried that I may change the fotogs desired result by changing the light to compensate for my bad monitor and in order to stay consistent I guess I need to make the same change to all pictures? |
Each of the 3 RGB channels of the images on this site (8-bit RGB) have 8 bits ber channel. Each channel is a greyscale image that represents one particular color, with 256 different shades of brightness.
Given that an 8-bit image can represent about 5 stops of light (the dynamic range of the image), the 256 different shades are divided amoung these stops. The distribution however is not linear, but rather the brightest stop is given half of the available shades (128), and then next half of whats left, and so on. This gives a break down of values available to each stop as follows (with 12-bit images the numbers are bigger, but the progression is the same):
1st stop - 128
2nd stop - 64
3rd stop - 32
4th stop - 16
5th stop - 8
The dark tones are represented by far fewer values than the lighter ones are.
The observations you made is a direct result of this. A small change in brightness can raise the darker tones a full stop without much trouble, but a brighter tone would only have a small change -- one that may be small enough to not even be noticed.
David
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09/18/2004 02:53:17 PM · #6 |
Thanks for that David - its much clearer to me now.
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09/18/2004 05:08:34 PM · #7 |
David, what is the basis of that information you posted? While it is true that linear ccd/cmos devices have their data distributed this way, you seem to be applying this theory to a non-linear (gamma adjusted) image.
The answer may be related to the way the S/H adjustment works. But if you're happy with any old answer that seems correct, then surely it doesn't matter what the real answer is anway.
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