A densitometer is a device that measures the degree of darkness of transparent or opaque surfaces, which is why it is considered a fundamental instrument for the study and quality of the image. In certain cases it is also called a “spectrodensitometer”.
Likewise, the reading is obtained through the degree of absorption or reflection obtained when applying a light source. Currently, the vast majority of these devices have electronic readers to give much more accurate results.
This tool is commonly used in the photographic and printing industry, as it is directly involved in the reproduction of photos and prints to achieve greater control regarding the quality of colors.
At this point it is important to take into account that each device has its own measurement scale, so it is necessary to familiarize yourself with those that are described in the device’s instructions.
A densitometer is a device that is capable of emitting light towards a specific point on the surface that is being analyzed, all this by means of a series of lenses that will be responsible for capturing the degree of reflection and light emission.
The light that is obtained, as the case may be, will be collected by a series of readers that will interpret the values electronically. Subsequently, the output will be compared with another reference number. In the end, the main screen will reflect the measurement in question.
It should be mentioned that when analyzing inks or color images, it will be important to rely on specialized filters and lenses in order to obtain an accurate figure. Therefore, it will be done in this way:
-When you want to analyze the magenta, the green filter will be used.
-If it is a cyan ink, red will be used.
-In case of yellow tones, it will be done with blue.
-As for the black, a neutral filter will be chosen.
Aspects to consider
If you want to achieve a correct reading, it is important to take into account a series of recommendations:
-It is important to make the pertinent calibrations every so often, otherwise, the values obtained will not be correct. Some specialists recommend doing it once a day.
-We must take into account the conditions in which the measurement in question will be made. It is good to lean on a black surface if you do not have a completely opaque space.
-As for the appliance, it is important to keep it clean and free of dirt. For example, it is vital not to rest your fingers, as fingerprint marks can affect the reading and measurement process.
-Filters and other lenses must also be cleaned frequently, as well as being handled with care.
-It is necessary to contrast the results to avoid disparities between the numbers obtained.
Mainly, there are two types of densitometers:
– Reflection : these are responsible for measuring the amount of light reflection on the opaque surfaces of printed materials. You can also find those that do color readings.
– Transmission : they measure the light that a transparent surface is capable of transmitting.
With regard to the above, it is important to note that there are tools that include the registration of values for color inks and black and white.
In the same way, there are teams that integrate different qualities , some have more refined lenses and others can be used for all types of printing material, even folded cardboard. Many others, meanwhile, specialize rather in reading dense black and white layer surfaces.
It is understood that there are two main types of uses in this regard:
Some of the main ones are named:
- To determine the correct type of paper to use when printing or developing.
- For the measurement of negatives.
- For the measurement of saturation in the printing process.
- To determine the exposure time required when printing or developing.
In all cases, when a correct calibration of the apparatus and the materials to be used is achieved, the result will be according to what the photographer or operator is looking for.
It allows to obtain a greater degree of quality control regarding the saturation of the colors at the time of printing. In this case, the densitometer is used to determine the measurement standard of the inks to be used.
However, there are some methods where the values of the densitometers are not applicable, so they rely on those obtained from the colorimeters. This is mainly because they give more accurate results.
At this point, some terms that are related to the densiometer can be highlighted:
– Colorimeter : it is a device used to measure and identify the color and the nuances that can be released from it. The colorimeter measures the degree of absorbency of a color, in proportion to its density. It allows a more precise study of colors.
Today it is considered one of the most important tools when making prints.
– Sensitometry : it is a process closely related to the world of photography, since it is an area that is responsible for studying photosensitive materials. Studies in this regard began at the end of the 19th century, in order to determine the density of the materials used in the development process.
– Densitometric filters : are those that allow the analysis of the different wavelengths found in the densities of opaque and transparent materials. They are currently standardized by ISO.
– Photosensitive material : in terms of photography, it refers to materials that are sensitive to light and that, therefore, are capable of reacting when exposed to it. Thanks to this, they become a means for obtaining images.
It is worth mentioning that photosensitivity occurs thanks to the intervention of materials and other chemical components.
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