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Mike Warren
Veteran Member
VG,
Just thought this was an interesting article that discusses Middle Grey, not knowing what the original poster was asking to begin with. Your comment, "The concept of the 18% gray card for traditional photography doesn't always carry over into digital" reminded me of this article-that's all. The article seems to backup your statement, but in a different context. (Just to add more confusion to this thread, I guess...)
Mike
Just thought this was an interesting article that discusses Middle Grey, not knowing what the original poster was asking to begin with. Your comment, "The concept of the 18% gray card for traditional photography doesn't always carry over into digital" reminded me of this article-that's all. The article seems to backup your statement, but in a different context. (Just to add more confusion to this thread, I guess...)
Mike
Check this out:Can anybody tell me please ?
Regards
Jusko
http://www.aim-dtp.net/aim/calibration/middle_gray/
Mike
---
http://www.pbase.com/mikew714
Okay, just curious. Anything by Timo has to be taken with a grain of salt with half being okay and the other half way out in left field. When I saw the link, I figured I better go ahead and set up my monitor for a 1.0 gamma if I wanted to view his stuff.
Thanx,
VG
Thanx,
VG
Just thought this was an interesting article that discusses Middle
Grey, not knowing what the original poster was asking to begin
with. Your comment, "The concept of the 18% gray card for
traditional photography doesn't always carry over into digital"
reminded me of this article-that's all. The article seems to backup
your statement, but in a different context. (Just to add more
confusion to this thread, I guess...)
Mike
Check this out:Can anybody tell me please ?
Regards
Jusko
http://www.aim-dtp.net/aim/calibration/middle_gray/
Mike
---
http://www.pbase.com/mikew714
J
Jusko
Guest
Thank you everybody for your input. In fact, I just wanted to make an 18% graycard with PS and printed with either a B&W laser printer or color inkjet printer.
Best Regards
Jusko
Best Regards
Jusko
J
Jusko
Guest
Thank you everybody for your input. In fact, I just wanted to make
an 18% graycard with PS and printed with either a B&W laser printer
or color inkjet printer.
Best Regards
Jusko
I knew the answer Digidog, because I had copied and saved the text below.
A good while ago the Dog said:
"RGB numbers don't tell you what a color looks like, only the recipe for that color. Every RGB space will have a different recipe for the same APPEARANCE of color."
"RGB and CMYK are DEVICE DEPENDANT color spaces. Give me a profile based on a set colorspace, I'll give you the values. Change the sapce, the values will change."
Always enjoy reading your stuff.
Patrick
A good while ago the Dog said:
"RGB numbers don't tell you what a color looks like, only the recipe for that color. Every RGB space will have a different recipe for the same APPEARANCE of color."
"RGB and CMYK are DEVICE DEPENDANT color spaces. Give me a profile based on a set colorspace, I'll give you the values. Change the sapce, the values will change."
Always enjoy reading your stuff.
Patrick
Zippy DooDah
Senior Member
Hi Jusko,
This discussion is amazing to me.
Phil's original answer was correct.... a Kodak 18% gray card will yield RGB values of 128, 128, 128 in Photoshop.
18% gray card just means that the card will REFLECT 18% of the incidental light falling on the card, while in Photoshop this is shown as a COLOR of 50% gray (hence the values 128,128,128).
It's probably not a good idea to try to make your own 18% gray card as it's unlikely your printer will give exact same values for R G and B.
Kodak gray cards are fairly cheap... they're like $6 for a small card and $15 for a package of two sturdy 8x10 cards. If you buy the Kodak 18% gray cards you're assured of getting the right white balance and/or exposure.
...Zippy
This discussion is amazing to me.
Phil's original answer was correct.... a Kodak 18% gray card will yield RGB values of 128, 128, 128 in Photoshop.
18% gray card just means that the card will REFLECT 18% of the incidental light falling on the card, while in Photoshop this is shown as a COLOR of 50% gray (hence the values 128,128,128).
It's probably not a good idea to try to make your own 18% gray card as it's unlikely your printer will give exact same values for R G and B.
Kodak gray cards are fairly cheap... they're like $6 for a small card and $15 for a package of two sturdy 8x10 cards. If you buy the Kodak 18% gray cards you're assured of getting the right white balance and/or exposure.
...Zippy
Jusko wrote:
Thank you everybody for your input. In fact, I just wanted to make
an 18% graycard with PS and printed with either a B&W laser printer
or color inkjet printer.
Best Regards
Jusko
as people have already pointed out, middle grey is NOT 128,128,128.
the exact value depends on gamma of the specific color space.
also, if the original poster is asking what values to get by taking a picture of 18% grey card, keep in mind that most cameras are calibrated to 13% or so, not 18%.
Ming
the exact value depends on gamma of the specific color space.
also, if the original poster is asking what values to get by taking a picture of 18% grey card, keep in mind that most cameras are calibrated to 13% or so, not 18%.
Ming
Hi Jusko,
This discussion is amazing to me.
Phil's original answer was correct.... a Kodak 18% gray card will
yield RGB values of 128, 128, 128 in Photoshop.
18% gray card just means that the card will REFLECT 18% of the
incidental light falling on the card, while in Photoshop this is
shown as a COLOR of 50% gray (hence the values 128,128,128).
Zippy DooDah
Senior Member
This is not helpful to Jusko.
What gamma do you think he's using? At 2.2 or 1.8, an 18% gray card will reflect 18% of the incidental light and Photoshop will show this as 128, 128, 128.
Most people (but not all) use the gray card for white balance, not exposure.
I don't know if you're correct about cameras using 13% instead of 18%... sounds very wrong to me.
I fail to see how your "correction" will be of any value to Jusko. He's simply trying to create his own 18% gray card. The best advice is to simply go buy a Kodak 18% gray card and use it for white balance. Bringing up gamma values does nothing to aid him in his understanding.
What gamma do you think he's using? At 2.2 or 1.8, an 18% gray card will reflect 18% of the incidental light and Photoshop will show this as 128, 128, 128.
Most people (but not all) use the gray card for white balance, not exposure.
I don't know if you're correct about cameras using 13% instead of 18%... sounds very wrong to me.
I fail to see how your "correction" will be of any value to Jusko. He's simply trying to create his own 18% gray card. The best advice is to simply go buy a Kodak 18% gray card and use it for white balance. Bringing up gamma values does nothing to aid him in his understanding.
Ming Wang wrote:
as people have already pointed out, middle grey is NOT 128,128,128.
the exact value depends on gamma of the specific color space.
also, if the original poster is asking what values to get by taking
a picture of 18% grey card, keep in mind that most cameras are
calibrated to 13% or so, not 18%.
Ming
Hi Jusko,
This discussion is amazing to me.
Phil's original answer was correct.... a Kodak 18% gray card will
yield RGB values of 128, 128, 128 in Photoshop.
18% gray card just means that the card will REFLECT 18% of the
incidental light falling on the card, while in Photoshop this is
shown as a COLOR of 50% gray (hence the values 128,128,128).
J
Jusko
Guest
Thank you very much for your help.
I just wanted to make an 18% graycard for WB. But after reading so much infomation, I think I would follow your advice to buy a Kodak Graycard.
I first thought that it would be very easy if I knew the RGB value for an 18% graycard. Then I could set that value in PS and fill a blank document with that color and print that out.
Thank you everyone for your help.
Best Regards
Jusko
I just wanted to make an 18% graycard for WB. But after reading so much infomation, I think I would follow your advice to buy a Kodak Graycard.
I first thought that it would be very easy if I knew the RGB value for an 18% graycard. Then I could set that value in PS and fill a blank document with that color and print that out.
Thank you everyone for your help.
Best Regards
Jusko
Phill Brannon
Veteran Member
I certainly never claimed to be an expert in the field of color management. I can assure you I'm no Bruce Fraser, and only know what I read and learn from people that have probably forgotten more on the subject than I know. I answered a simple question with a simple answer. Since the zone system was devised 18% gray has been considered middle gray "the point half way between true white and true black that reflects 18% of available light", of course you can get into other issues here with reflectance and all sorts or variables. Those of us that cut our teeth on film many years ago have used Kodak gray cards and this has always been the standard. This has been a healthy discussion though, and I've enjoyed the input. Below is Thom Hogan's view on the subject.
http://www.bythom.com/graycards.htm
Pbase supporter
http://www.bythom.com/graycards.htm
--Thank you very much for your help.
I just wanted to make an 18% graycard for WB. But after reading so
much infomation, I think I would follow your advice to buy a Kodak
Graycard.
I first thought that it would be very easy if I knew the RGB value
for an 18% graycard. Then I could set that value in PS and fill a
blank document with that color and print that out.
Thank you everyone for your help.
Best Regards
Jusko
Pbase supporter
Jusko,
Part of my business is profiling systems including digital cameras. One of the biggest mistakes that I see with the pros that I deal with is that they use one of the 'gray' cards like Kodak or print their own. The majority of these cards have a high specular composition and can easily throw off WB in any camera. Of course, you have people that use them all the time and are perfectly happy with them until they're shown the difference.
I would suggest a setup like the Whibal system here:
http://www.rawworkflow.com/products/whibal/index.html?p=23880#post23880
if you're serious about your imaging.
Regards,
VG
Part of my business is profiling systems including digital cameras. One of the biggest mistakes that I see with the pros that I deal with is that they use one of the 'gray' cards like Kodak or print their own. The majority of these cards have a high specular composition and can easily throw off WB in any camera. Of course, you have people that use them all the time and are perfectly happy with them until they're shown the difference.
I would suggest a setup like the Whibal system here:
http://www.rawworkflow.com/products/whibal/index.html?p=23880#post23880
if you're serious about your imaging.
Regards,
VG
Can anybody tell me please ?
Regards
Jusko
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