Blogs
RGB v Tristimulus Color Scales – HELP!
Posted on by Ganesh Ramanathan
At my new quality assurance job, one of our product quality checks is to measure the color of our product and to ensure that we are producing our product that is within a preset acceptable color range. We use an instrument, a spectrophotometer, that reports Hunter L, a, b; XYZ, and L*a*b scales. I’ve always thought […]
ASBC Beer Color and Turbidity
Posted on by Ganesh Ramanathan
ASBC Color The ASBC Beer Color scale has a range of approximately 1 to 11 units, with the more yellow, pale worts at the low end of the scale and the redder color of dark worts, beers and caramels at the upper end of the scale. The industry reference method for ASBC Beer Color and […]
Carbon Blackness [My], Jetness [Mc], Undertone [dM] and Tint Strength [T]
Posted on by Ganesh Ramanathan
“Carbon black, also called charcoal black lamp black, pigment black, soot or black carbon, is a fine particle carbon pigment obtained as soot from the incomplete combustion of many different types of organic materials, such as natural gas, or oil. Carbon black is usually a fine, soft, black powder. It is very stable and unaffected […]
How do you validate a APHA/Pt-Co/Hazen 500 liquid color standard?
Posted on by Ganesh Ramanathan
As described in Section 6 of ASTM D1209, there are 2 criteria to validate a APHA/Pt-Co 500 standard:
What is Y Transmission?
Posted on by Ganesh Ramanathan
In addition to representing green in the CIE X, Y, Z tristimulus color scale, the CIE Y is also the 1924 CIE Luminosity or Brightness function which quantifies the way people perceive the relative brightness of equal energy spectral hues. Humans perceive green colors as brighter or more luminous than blue or red.
What is Hunter Whiteness Index?
Posted on by Ganesh Ramanathan
Hunter Whiteness Index [WIH] There are at least half a dozen whiteness indices in use today, and a similar number of legacy whiteness indices no longer in use. There are subtleties among them and it is important to know the forms of these whiteness metrics and conditions for which they are derived for. In general, […]
Do you have a source for EP Opalescence Standards?
Posted on by Ganesh Ramanathan
The reference document that defines the visual EP Opalescence scale is: EP 2.2 Physical and Physico-Chemical Methods for color and opalescence EP – European Pharmacopoeia, Section 2.2 Physical and Physico-Chemical Methods, Unit European Pharmacopeia, Strasbourg, France (1997: 15-16) www.pheur.org This method describes the visual evaluation of scattering or opalescence in near clear liquids, typically pharmaceutical, […]
Do you know what Molten Color is?
Posted on by Ganesh Ramanathan
FAQ:”A client is asking me to measure something they call “Molten Color’. Do you have any information on this? Do Hunterlab instrument have a function for this color?”
Do you have references for the equivalency of CIE inverse instrument geometries?
Posted on by Ganesh Ramanathan
FAQ: “…. the schema of the principle of measuring shows other way of light (source of light -> sample -> sphere -> detector) than our ColorQuest (source of light -> sphere -> sample -> detector). Please can you explain me difference between both construction? difference between both results of measuring?”
Can you explain the LabScan XE 0:45 inverted geometry?
Posted on by Ganesh Ramanathan
FAQ: “Straight from the LSXE Pro-forma, the LabScan XE sample ports are described as: Port Insert, 3-mm illuminated area; 5-mm measured area Port Insert, 6-mm illuminated area; 10-mm measured area Port Insert, 13-mm illuminated area; 17-mm measured area Port Insert, 25-mm illuminated area; 30-mm measured area Port Insert, 44-mm illuminated area; 50-mm measured area I […]
Do you have a source for Magnesium Carbonate powder as top-of-scale?
Posted on by Ganesh Ramanathan
For measuring the brightness of some materials, some dated industrial methods cite a Magnesium Carbonate block standard to be set to Y = 100% in reflectance. This is a very old top-of-scale standard and HunterLab does not recommend using it.