Image Processing Flashcards by Brandon Makowski

If film is exposed to white light or ionizing radiation, what 2 options can be used to prevent that?

Daylight system – consists of an automatic film unloader that takes the sheet of film out of the cassette and moves it directly into a film processor.
Darkroom - functions to protect the film from white light and ionizing radiation during handling and processing

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Darkroom function

Protect film from:

Visible light
• Ionizing radiation
• Excess heat and humidity • Static electricity
• Pressure
• Chemical fumes

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Film processing functions

Converts latent image to manifest image
• Preserve image for permanent storage

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What are the 2 basic methods used for film processing?

Manual – film is transported through each step by hand.
• Automatic – electro-mechanical device that transports film through various solutions

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Processing chemistry developer

Most important processing step
Converts latent image to manifest image
Uses oxidation/reduction reaction

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Development

First stage in processing of the radiograph
Amplifies latent image by 100,000,000
Converts invisible latent image into visible form

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Latent image

Bromide ions react with silver ions to form metallic silver ions, and eventually get a cluster of them

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Developer or Reducing agents

Phenidone - Fast acting producing optical densities under 1.2
Hydroquinone - slow acting, producing optical densities above 1.2

Uses Synergism or Superadditivity
Most hazardous processing solution, very high pH

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Accelerator, Activator, or Buffering Agents

Maintain alkaline medium
Soften and swell film emulsion - gives more area for develop solution to do its activity

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PH scale

Developer should have a pH of 10-11.5

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Restrained, regulator, anti-foggant, or starter

Restrains the action of developing agents to help prevent chemical fog

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Preservative

Helps prevent premature oxidation

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Premature oxidation can be caused by:

Aerial- contact with air
Internal - contact with other ingredients in developer
Photo - exposure to light

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Hardener

Keeps film emulsion from sticking to rollers in processor
Weaker hardener than in fixer solution
Glutaralehyde is used

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Solvent

Other components mixed with solvent, creates developer solution
Water is used

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Sequestering agent

Used for developer solutions mixed from concentrate
Keeps impurities in tap water from oxidizing reducing agents

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Ready or premix

Easier but more expensive

Concentrate

40% cheaper but less convenient
Must be mixed properly from kit

Developer activity factors

Solution Temperature
• Immersion Time
• Solution Concentration • Type of Chemicals
• Solution pH
• Exhaustion/Replenishment

2 most important factors for film processing

Time
Temperature

Optimum temperature range fo film processing

68-72 degrees Fahrenheit

Ideal time and temp

5 minutes @ 68 degrees Fahrenheit

What should be done when film is in the developer?

Agitate it to remove build up of halogen gas bubbles
If not done, uneven development can occur

Replenishment

Overtime, developer becomes exhausted

Fixer

Has 4 major functions: 1.stop further development 2. To clear the image 3. To fix image 4. To complete the process of hardening of the film emulsion

Reasons for replenishment

Oxidation occurs to quick Acid compounds form A lot of developer is consumed

Fixer components

Fixing agent - Removes unexposed and undeveloped silver halide crystals Preservative - Helps recycle fixing agent Acidifier - Provides an acid medium for the fixing agent so that it can remove the unexposed and undeveloped silver halide crystals. Hardener or tanning agent - Permanently hardens film emulsion for long-term archival storage • Hardening process is also called tanning Sequestering agent - Helps prevent development of aluminum hydroxide Solvent

Fixer is available in what?

Concentrate kit

Washing

Film must be washed well with water Removes all thiosulfate complexes Tap water is used Incomplete wash causes retained hypo to react with silver

Drying

Surface water and most retained in emulsion layer should be removed

Manual processing

More time required More space Lower cost Better image quality Less quality control

Automatic processing

Shorter time required Less space required Higher cost Chemical fog Better quality control

Automatic processor main systems

Transport System • Temperature Control System • Circulation System • Replenishment System • Dryer System • Electrical System

Transport system

largest and most complex system • Made up of many moving parts, so is most likely to break down • Controls Processing Time

Transport system consists of:

Roller subsystem • Transport-rack subsystem • Drive subsystem

Temperature control system

Regulates solution temp Water controlled system Thermostatically controlled-most common

Circulation system

Also known as recirculation and filtration system • Ensures complete chemistry mixing • Provides uniform temperatures • Provides equivalent of agitation performed in manual processing

Replenishment system

Used to replenish developer and fixer solutions Available in volume, and flood

Dryer system

Consists of 2 to 3 heating units

Electrical system

Distributes electrical power

Types of automatic processors

7 and 3 minute, 90,60,45 second

Multispeed

transport system speed can be varied to select different combinations of the above