Edcculus
Well-Known Member
Excuse the extreme geeking out in this thread. I feel like I am excused since this is the "brew science" section.
I'm suprised I haven't read through this material before. After all, I am a Color Management Specialist at a printing company.
When I first heard about SRM, I immediately realized what the links in this thread (especially the second one) say abou the limitations of SRM. In printing terms, SRM most closely resembles how we measure the whiteness of paper. Whiteness is a measure of the reflectance of light at 457nm by a spectrophotometer. In these terms, SRM is merely a factor of how light passes through a beer.
In the printing industry, we have color viewing and measurement standards. We obviously have a much wider range of colors to describe. In general, a three value system is used to quantify numbers. Most people and programs use L*a*b* color space. I find the CIE LCH system more intuitive. Basically it describes color according to lightness, chroma and hue. Lightness is how light or dark a color is. Chroma is how saturated it is. Hue is the actual color.
To measure beer color correctly one would need to do a flow cell analysis. Sorry no link. I forget what the instrument is called since I haven't used one since my Junior year in college. This instrument is used to measure the pure color of ink. You dillute the ink at a certain rate. You pour it into a system that feeds it into a very thin clear tube. A spectrophotometer then reads the spectral data.
I believe the very same instrument and software could be used to very accurately measure the color of beer. I am willing to bet that a certain large brewery uses a very similar method so their extremely pale lagers all come out the same color. If not, I need to put in my resume!
I'm suprised I haven't read through this material before. After all, I am a Color Management Specialist at a printing company.
When I first heard about SRM, I immediately realized what the links in this thread (especially the second one) say abou the limitations of SRM. In printing terms, SRM most closely resembles how we measure the whiteness of paper. Whiteness is a measure of the reflectance of light at 457nm by a spectrophotometer. In these terms, SRM is merely a factor of how light passes through a beer.
In the printing industry, we have color viewing and measurement standards. We obviously have a much wider range of colors to describe. In general, a three value system is used to quantify numbers. Most people and programs use L*a*b* color space. I find the CIE LCH system more intuitive. Basically it describes color according to lightness, chroma and hue. Lightness is how light or dark a color is. Chroma is how saturated it is. Hue is the actual color.
To measure beer color correctly one would need to do a flow cell analysis. Sorry no link. I forget what the instrument is called since I haven't used one since my Junior year in college. This instrument is used to measure the pure color of ink. You dillute the ink at a certain rate. You pour it into a system that feeds it into a very thin clear tube. A spectrophotometer then reads the spectral data.
I believe the very same instrument and software could be used to very accurately measure the color of beer. I am willing to bet that a certain large brewery uses a very similar method so their extremely pale lagers all come out the same color. If not, I need to put in my resume!