Density vs Spectral Density

[Castek]

I would like to understand the distinctions between the following terms:

Density

Spectral Density

I understand that Density is a measurement of the amount of light that reflects from ink, and I also understand the nature of spectral measurement data. Where I am not clear is which one might be preferred when limiting channels of ink. Thanks for any light you can shine on this topic (pun intended).

 

[Deleted member 16349]

I would like to understand the distinctions between the following terms:

Density

Spectral Density

I understand that Density is a measurement of the amount of light that reflects from ink, and I also understand the nature of spectral measurement data. Where I am not clear is which one might be preferred when limiting channels of ink. Thanks for any light you can shine on this topic (pun intended).

Density is not measured directly. It is a calculation from the reflection values obtained by one of the RG or B filters in a densitometer. D = log 1/ref

Not exactly sure what Spectral Density means in your question but density values can be obtained with a spectrometer that measures reflectance over the whole spectral range and then applies a function to mimic the filters used in the densitometer to get the specific reflectance. It then calculated density.

Hopefully I have remembered the equation correctly.

 

[rich apollo]

I understand that Density is a measurement of the amount of light that reflects from ink, and I also understand the nature of spectral measurement data. Where I am not clear is which one might be preferred when limiting channels of ink.

Density calculated from spectral measurement is gonna' be better for inks whose spectral properties don't align well with densitometric filters. For example, I don't think your old Xrite 404 has a good filter for orange.

The point is probably moot, as I believe all instrument manufacturers have moved to spectrodensitometry.