Equidensitometry

Equidensitometry is the technique of measuring equidensities in a photographic deposit or photographic layer, such as photographic films and photographic plates

Equidensitometry

Equidensitometry is the technique of measuring equidensities in a photographic deposit or photographic layer, such as photographic films and photographic plates.

  • Equidensities are points, lines and areas having equal densities also called isodensities.
  • First order equidensities are points, lines and areas having isodensities obtained by applying one of the listed below techniques once, thus they exhibit one particular Density in the original
  • Second order equidentities are points and lines having isodensities obtained by applying one of the listed below techniques twice, thus they exhibit two particular Densities in the original. Second order equidensities do not normally show areas.
  • Equidensity series is a sandwich (in register) of a number of different equidensities. Usually each equidensity is coded by color or raster.

Photographic and computerized image processing techniques

Four techniques of obtaining equidensities are:

Applications

Interpretation or measurement of an image is sometimes aided by simplification of the density pattern.[2] This results in data reduction and enables keying (areas or lines with iso-densities to unique patterns, grey values or colours). This keying to singular grey- or colour values is known in modern image processing as using L.U.T.s.[3]

The fact that a certain density of a photographic layer has been caused by a specific amount of actinic radiation (visual light, UV-light, X-rays, autoradiography, etc.) can be used to qualify and perform spatial measurements of a physical phenomenon. A calibrated photographic process is used to obtain quantitative measurements as well.

Equidensitometry with Agfacontour made it possible to obtain reproducible equidensities similar to pseudosolarized photographic films and prints. The Agfacontour film contained two special emulsions with each different spectral sensitivity. Using color filters (yellow or magenta) during the exposure on Agfacontour one could control the width of the equidensity. By varying the exposure one could change the density in the image that showed on Agfacontour as equidensity. Although the material exhibited very low sensitivity (long exposures were necessary) the results were very reproducible and second order equidensities were sharp and clear, something that with pseudosolarization was almost impossible to achieve without special procedures.[4][5]

In the following fields equidensitometry is used extensively:

  • Flash against white wall
    Flash against white wall
  • Flash against white wall, equidensities serie of the first order (sandwiching several equidensities transparencies)
    Flash against white wall, equidensities serie of the first order (sandwiching several equidensities transparencies)
  • X-Ray image of right hand with no details in the bones at the bottom of the image
    X-Ray image of right hand with no details in the bones at the bottom of the image
  • Original: X-Ray image of right Hand; 1st. order equidensities after pseudo-solarization of original
    Original: X-Ray image of right Hand;
    1st. order equidensities after pseudo-solarization of original
  • Original: X-Ray image of right hand; colored 1st. order equidensity-series using pseudo-solarization, B&W copies chromogenic developed
    Original: X-Ray image of right hand;
    colored 1st. order equidensity-series using pseudo-solarization, B&W copies chromogenic developed

See also

References

  1. ^ Guyer, Jeff (24 September 2013). "The Sabattier Effect". Digital Photography School. Retrieved 2019-01-09.
  2. ^ a b Applied Photography, Arnold et al, Focal Press, pages 422–426
  3. ^ Baler, Kevin (Gali) (2004-04-06). "LUT Editor". Archived from the original on 2016-12-16. Retrieved 2019-01-06.
  4. ^ US 6083671, Yurow, Harvey Warren, "Photographic developer for direct production of equidensity images on a high contrast film", published 1999-07-19, issued 2000-07-04 
  5. ^ a b c d e f g h i j Agfacontour Professional in Wissenschaft und Technik, C. Sauer, Agfa-Gevaert AG Druckschrift nr. 152, 1. Auflage 1974 (in German)
  6. ^ Myšák, F. (1973). "The Evaluating of Autoradiographs by Means of the Film Agfacontour Professional". Journal Isotopenpraxis Isotopes in Environmental and Health Studies. 9 (8): 280–281. Bibcode:1973IIEHS...9..280M. doi:10.1080/10256017308543671.
  7. ^ Nielsen, U. (1972). "Agfacontour Film for Interpretation" (PDF). Photogrammetric Engineering: 1099–1105. Retrieved 2019-01-22.

Content Disclaimer

Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.

  1. The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
  2. There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
  3. It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
  4. Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
  5. Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.