Talk:Densitometry

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Comment[edit]

Does anyone know the unit of measure for density? I regularly measure film density, but no one I've spoken to seems to know what what a density of 3.1 actually means.

According to the optical density article, 3.1 units of density refer to 3.1 orders of magnitude (1260 times) for test light attenuation. This is usually denoted as “3.1 D”, where letter “D” stands for Driffield, but most people think that it is initialism for “density”. It's very strange that those trivias are still missing in Wikipedia. 213.234.235.82 (talk) 12:03, 30 October 2008 (UTC)[reply]

This article only address transmissive densitometry. Should I add something about reflective densitometry and/or in graphic arts at least it compares to a spectral measurement?

I actually came across this article looking for information about what you two talked about, the actual units of measurement in density, but was kind of surprised that the article didn't mention reflective density.

What do you think? 75.135.154.19 (talk) 04:44, 20 November 2008 (UTC)[reply]

Saw "densitometry" on a page explaining the "BodPod." This is anything but optical to get body density measurements. Anyone? —Preceding unsigned comment added by 138.162.128.52 (talk) 13:28, 27 July 2009 (UTC)[reply]

Different wording of the definition and addition of references[edit]

I like to propose a different wording of the definition of Density. Using references such as:
Spencer, D A (1973). The Focal Dictionary of Photographic Technologies. Focal Press. ISBN 0-240-50747-9,
The Focal Encyclopedia of Photography (Desk ed.). London: Focal Press Ltd. 1976

Thus the most universal definition as I see it is:
Densitometry is the determination of the optical density of photographic deposits to either transmitted or reflected light by either a visual or photoelectric photometer (densitometer) which measures the intensity of a beam of light before and after passing through the deposit.

Problems with the current definition:[edit]

Densitometry is also quantitative and should be mentioned as the amount of the deposit of silver or printing ink (see below)
There is also a subjective form of density which is the relative darkness of an image area as seen by the eye
The result of optical density is by exposure to actinic radiation AND subsequent development of the photographic material
Actinic, photographic radiation is usually light from natural or artificial sources, but can be anything from X-Rays to near Infrared
Optical density in photographic papers or printed matter is by nature reflected optical density whereas in photographic films the optical density is by transmission of the light through the photographic layer(s).

Thus the the sentence which has the wording "shines through" I would change into: "...is transmitted through a transparent film or reflected by a paper having a photographic image on its surface." Also the reference to absorptiometry is not used in photographic imaging but in X-ray absorptiometry measuring the density of bone minerals. The reciprocal of transmittance in densitometry is Opacity; see Opacity (optics) and one should not use "absorbance or density".

It should also be mentioned that densitometry is widely used in the printing industry to evaluate, control and adjust printing process, ink quantities and half-tone screen variables. Here the 'deposit' in above definition is the ink printed on paper.

In the article there should be a section about color densitometry.

--Photojack50 (talk|contribs) 14:50, 20 January 2019 (UTC)[reply]