Matthieu DUBAIL wrote:
Here is what I thought: Colorimeters are better for displays. Unlike printed paper, displays have deep blacks. Spectrocolorimeters are weak on low luminance measurement cause they have narrow spectral bandwith, unlike colorimeters.
Think about it: If you take the same amount of light and split it up into narrow spectral bands, then yes, the measurement for each band has a lower s/n ratio than splitting the light into (say) 3 bands. But then those spectral measurements are weighted and summed again using the standard observer curves, cancelling the noise out in proportion to the number of bands being summed, and improving the s/n ratio. But a colorimeter using passive filters (rather than a diffraction grating or dichroic filters), would need 3 times the sensor area because it is throwing light away in the filters. So it is not the spectral nature of the spectrometer that is important in the overall s/n ratio of XYZ values, it is the amount of light captured and the efficiency of the filtering and measuring that is important. In general it is easier (ie. cheaper) to make a colorimeter that collects a lot of light than a spectrometer. But have you examined the types of sensors used in most cheap display colorimeters ? I have, and they are typically off the shelf light to frequency converters, with very small sensor areas. So no advantage is being taken of this possible avenue of advantage towards colorimeters. [The only exception is the DTP92/94] So in practice the s/n ratio of something like the i1pro or ColorMunki is actually better than these cheap colorimeters when using comparable integration times.
Every display models I heard of (form simplest to most complicated) are colorimetry based.
If you are talking about device models, then this simply reflects the fact that displays are typically additive devices, and therefore tri-stimulus models are good enough. But this isn't always the case :- for instance, if you want to model a projector reflecting from a screen, you need to use a spectral model to account for the screen.
Spectrocolorimeters might miss spectral peaks (like those found on CRT red primaries, fluo and led LCD backlight) depending their spectral bandwith and overlap.
They typically don't miss reading energy from any wavelength, since the gaps between the sensors is quite small, and the optics spreads narrow peaks somewhat. The chief drawbacks of (an affordable) spectrometer is wavelength calibration accuracy and stability, and the observer curve quantization that occurs due the discrete nature of the wavelength measurements.
Spectrocolorimeters are better for printer. Some printers models are based on Neugebauer primaries or other multispectral model, computed form spectral datas.
Sure, but this has nothing directly to do with the measurement device. Of course you need spectral measurements to feed into a spectral model, but this doesn't imply that you need a colorimeter to make measurements to feed into a tri-colorimetric model. You just need tri-colorimetric values, which can (much more flexibly) be derived from spectral values. Graeme Gill.