Presentation on theme: "5 Image Capture Media. 5 Image Capture Media Describe the differences between digital image capture and the traditional chemical method of image capture."— Presentation transcript:
3 Describe the differences between digital image capture and the traditional chemical method of image capture.Explain the operation of a sensor in capturing an image.Distinguish between the physical structures of black-and-white film and color film.Explain the method by which a latent image is formed.
4 Describe the film speed rating system as a measure of sensitivity to light. List the various types and forms of film.List the advantages and disadvantages of color negative and color positive films.Demonstrate the film loading procedures for common types of cameras.
5 Digital vs. Film Image Capture Electronic arrays capture images on photo sitesDigital sensor captures imageCamera processes imageFile stored on removable deviceFilm records a latent imageMade permanent by chemical processing
6 Digital vs. Film Image Capture (Cont.) Photography long considered an image-capture process requiring chemicals and lightDigital photography far more popular than filmPixels arranged to form area arrayDigital images stores as files
8 Digital Imaging Process Light strikes pixelGenerates electrical chargeCharge strength varies with brightnessElectrical charge converted to analog signalAnalog signal converted to digital signal processed by camera’s firmwareCCD and CMOS devices process signals differently
10 Digital Cameras See Only Gray Bit depth determines gray levels1-bit pixel = 2 shades (black or white)8-bit pixel = 256 shadesColor information records filtered light to obtain grayscale channels
11 Bayer PatternFilter decals on pixelsTwice as many green filters
12 Sensor Sizes Full-frame print (24 mm 36 mm) APS-size (17 mm 30 mm) Same as 35 mm filmMost professional camerasAPS-size (17 mm 30 mm)Compact and prosumer cameras
13 Pixel Sizes Full-frame pixels 1/3 larger than APS More light-sensitiveExisting pixel values averaged to create new pixels through interpolation
14 Scanning Backs and Studio Cameras Linear arrays used exclusivelyTrilinear arrays preferred to area arraysLong exposures generate heat which can cause digital noise and blooming
15 Digital Image StorageMemory card flexible removable memory device
16 Digital File Formats Files may be compressed to use less storage space RAWTIFF (.tif)JPEG (.jpg)
17 Removable Storage Devices Secure Digital (SD)CompactFlash (CF)Capacities from 128 Mb–64 gigabytes (GB)Memory StickxD-PictureMicrodriveSmartMediaLexar/SanDisk/Fujifilm/Sony Corporation/Hitachi
18 Storage CapacitiesDepends on sensor size and file type
19 Card Speed Transfer rate from camera to card Useful for sports and action photographyCameras also possess a buffer, or internal memory
20 Film Image Capture Evolution of film Daguerrotype/tintype Wet (collodion) glass platesDry (silver bromide) glass platesRoll film
21 Physical Structure of Film Flexible base materialLight-sensitive (emulsion) layer(s)Special-purpose layers
22 Black-and-White Film Film base Single emulsion layer Three additional layers:SupercoatSubbing layerAntihalation layerSurfactant used as wetting agent
23 Color FilmFilm baseThree emulsion layersFive additional layers
24 How Light Affects Film Photons affect silver halides Silver bromide ionsSilver bromide crystals contain sensitivity specksSilver clumps form latent imageNegative density proportional to lightPositive (print) will reverse values
25 Characteristic Curve Relates exposure to density Different for each filmFirst section = film base plus fogMiddle-density section = straight-line sectionRight end = shoulder
27 Film Speed Ratings Measurement of light-sensitivity Lower number = less sensitiveHigher number = more sensitiveSensitivity doubles/halves with each ISO stepFilm grain increases with speedBased on requirements by International Standards Organization (ISO)
28 Film Speed/Grain Relationship Grain increases along with film speedFilm emulsion improvements reduce grains at high speedsTabular grainsChromogenic film produces a grainless black-and-white image
29 Reversal Film Transparency is “first generation” image Exposure more critical than print filmTwo-step development processNegative silver imageColor dyes (positive) replace silver
30 Negative/Positive Film Most common film typeMonochrome and colorWide range of speedsProcessing readily availableDeveloped film is negativePrint is positive (“second generation”) imageHigh-contrast lithographic film
31 Instant-Print Film Film + developer Mostly replaced by digital imaging Print in 60 seconds or lessMonochrome and colorMostly replaced by digital imaging
32 Forms of Film Cartridge film Film in cassettes Almost obsolete 35 mm and APSDrop-in loadingLighttight cassette protects filmFilm loader required
33 Forms of Film (Cont.) Roll film Sheet film Medium-format cameras Paper backing holds/protects filmSheet filmIndividual, thicker film sheetsMust be used in holders4″ 5″ most common today
34 Where do the similarities between traditional and digital image capture end? When the light rays reflected from the subject reach the camera’s image receiver.
35 Many digital camera sensors have red, blue, or green color filter decals applied over the individual pixels in an arrangement called a _____ pattern. A. Bartel B. Bayer C. Boxcar D. Bizet
36 Color film may have as many as nine layers, including _____ separate emulsion layers. three
37 True or False? Photons of light striking the film emulsion form a latent image. True
38 Film with an ISO rating of 400 is ____ times more sensitive to light than an ISO 100 film. four
39 Antihalation layer APS-size The bottommost layer of film, located on the back side of the base. This layer prevents light rays from being reflected back through the base and emulsion. Without this layer, reflected light could form halos (halation) around bright objects in the photograph.APS-sizeSensor used in most digital cameras. The sensor is approximately 17 mm 30 mm in size, like the film used in Advanced Photo System cameras. (Full-frame sensors are 24 mm 36 mm, corresponding to the 35 mm film frame.)
40 Area array Bit depth Blooming A grid made up of rows and columns of electronic sensors.Bit depthA numeric expression of the number of shades of gray a pixel is capable of displaying.BloomingIn a digital photo, the smearing or bleeding of some color pixels, especially red, into adjacent parts of the image.
41 Buffer Card speed Characteristic curve Internal memory in the camera that functions as a holding tank for image information already processed but not yet transferred to the memory card.Card speedA measure of how rapidly image files can be transferred from the camera to the memory card.Characteristic curveAn S-shaped graph that serves as a “snapshot” of a given film’s reaction to light. It shows the relationship between exposure and density increase.
42 Chromogenic film Collodion A type of black-and-white film that produces an essentially grainless image composed of dyes, rather than silver.CollodionA basic emulsion ingredient of the wet-plate process, consisting of cellulose nitrate dissolved in ether or alcohol. A halogen salt such as potassium iodide also is dissolved in the mixture.
43 Color information CompactFlash (CF) Red, green, and blue values recorded by filtering the light striking the digital sensor to obtain three different grayscale channels.CompactFlash (CF)A small, solid-state memory card, available in a wide range of capacities, that is slipped into a slot on the camera.
44 Compressed file Digital noise One that has been converted to a format that allows it to be saved in a smaller size to take up less storage space or to speed up transfer time.Digital noiseTiny light-colored spots especially noticeable in shadow areas of a scan or image capture.
45 Digital signal Drop-in loading Image information that is encoded as a series of on/off states (usually represented by 1 or 0), rather than varying continuously (an analog signal).Drop-in loadingA feature of Advanced Photo System cameras that allows the consumer to merely open a film door on the camera and insert the cassette. The film is then automatically loaded and advanced to the first frame.
46 Electronic array File File formats An arrangement of millions of tiny solid-state photo sites used to capture an image in a digital camera.FileAn individual digital image that can be stored, transferred, or manipulated.File formatsDifferent modes of saving image data, such as JPEG or TIFF.
47 FilmA light-sensitive, silver-based emulsion coated on a smooth, usually flexible plastic, base.Film base plus fogThe minimal density of a clear film area, such as the strip between frames. The tiny amount of density is caused by the processing chemicals (rather than light). Also, a short, horizontal section at the left end of the characteristic curve.
48 Film loaderA lighttight device that holds a roll of bulk film and allows a desired number of frames of film to be wound into a cassette.Film speedThe film’s sensitivity to light—the higher the film speed, the less light is needed to create a latent image on the emulsion.
49 Filter decals Firmware Transparent color overlays applied in a checkerboard pattern over individual sensors in a CCD or CMOS array. There are usually twice as many green filters as red or blue filters, because human vision is most sensitive to the light values contained in the green channel of a color image.FirmwareThe built-in program found in a digital camera or similar device.
50 Full-frame print Gigabytes (GB) Gray levels A print made without cropping. A full-frame print from a 35 mm negative on an 8″ 10″ sheet would result in an image approximately 6 ½″ 9 ½″.Gigabytes (GB)A quantity used to describe storage capacity of digital devices, such as computer memory or camera memory cards; approximately equal to 1 million bytes.Gray levelsThe distinct “steps” between pure white and pure black.
51 Image-capture process Using a camera to record a scene on film or a digital sensor.International Standards Organization (ISO)A body that publishes standard sets of requirements to ensure uniformity of such items as film speeds.InterpolationIn scanning or image-editing applications, the creation of new image pixels by averaging the values of the surrounding existing pixels.
52 IonsAtoms carrying a positive or negative electrical charge.JPEGThe most common compressed file format, developed by the Joint Photographic Experts Group. It can be used to reduce file size by a small or large amount.Latent imageA photographic image that will not become visible until developing chemicals are used to bring it out and make it permanent.
53 Linear array Lithographic film Memory card Image-capture arrangement consisting of a long array containing only one to three rows of CCDs. Linear arrays are used in scanning-back cameras for studio work, and in flatbed scanners.Lithographic filmA high-contrast material that produces an image without graduated tones. The film is either black or clear. Sometimes referred to as “lith film”.Memory cardA digital storage device used in cameras; available in a number of forms and a wide range of capacities.
54 Memory Stick Microdrive RAW A form of memory card used primarily in Sony cameras.MicrodriveA tiny hard drive the size of a CompactFlash memory card.RAWFile containing the basic image information captured by the camera’s sensor and saved with a minimal processing.
55 Scanning backs Secure Digital (SD) Sensitivity specks Studio capture devices that make use of a trilinear array, rather than an area array.Secure Digital (SD)Memory cards that are physically smaller and thinner than CompactFlash cards, and are available with capacities from 128Mb to 8Gb.Sensitivity specksImpurities believed to play the important role of focal points or sites for the formation of the silver clumps making up the latent (undeveloped) photographic image.
56 Shoulder Silver halide salt SmartMedia The right end, or high-density portion, of the characteristic curve, representing the highlights of a scene.Silver halide saltA light-sensitive chemical compound used as a key ingredient of photographic emulsions.SmartMediaAn early form of removable memory card for digital cameras.
57 Straight-line section The middle-density portion of the characteristic curve, where the density/exposure relationship is most nearly proportional.Subbing layerA very thin coating of pure gelatin that helps bond the emulsion to the base.
58 Supercoat Surfactant Tabular grains The very thin, tough topmost layer of the film. Its primary purpose is to protect the emulsion from abrasion during exposure and processing.SurfactantAn ingredient of the film’s supercoat that promotes absorption of processing chemicals to help ensure even development.Tabular grainsA thinner flatter form of silver halide grains, developed to allow an increase in film speed without a corresponding increase in visible grain.
59 TIFF Trilinear array xD-Picture Tagged Image File Format. In a scanner or scanning back, a bar containing three rows of sensors that is moved across the image capture area. One row of sensors is filtered to capture red wavelengths; one is filtered for green, and the third is filtered for blue.xD-PictureTiny memory cards, about the size of a postage stamp, used in some digital cameras. They are available in capacities of 16Mb to 2Gb.