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C H A P T E R 5 Image Capture Media Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. O B J E C T I V E S Describe.

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Presentation on theme: "C H A P T E R 5 Image Capture Media Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. O B J E C T I V E S Describe."— Presentation transcript:

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2 C H A P T E R 5 Image Capture Media

3 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. O B J E C T I V E S 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. O B J E C T I V E S 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital vs. Film Image Capture Electronic arrays capture images on photo sitesElectronic arrays Digital sensor captures image –Camera processes image –File stored on removable device Film records a latent imageFilmlatent image –Made permanent by chemical processing

6 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital vs. Film Image Capture (Cont.) Photography long considered an image-capture process requiring chemicals and lightimage-capture process Digital photography far more popular than film –Pixels arranged to form area arrayarea array Digital images stores as filesfiles

7 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Film Capture and Processing

8 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital Imaging Process Light strikes pixel Generates electrical charge Charge strength varies with brightness Electrical charge converted to analog signal Analog signal converted to digital signal processed by cameras firmwaredigital signalfirmware CCD and CMOS devices process signals differently

9 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital Imaging Process (Cont.)

10 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital Cameras See Only Gray Bit depth determines gray levelsBit depthgray levels –1-bit pixel = 2 shades (black or white) –8-bit pixel = 256 shades Color information records filtered light to obtain grayscale channelsColor information

11 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Bayer Pattern Filter decals on pixelsFilter decals –Twice as many green filters

12 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Sensor Sizes Full-frame print (24 mm 36 mm)Full-frame print –Same as 35 mm film –Most professional cameras APS-size (17 mm 30 mm)APS-size –Compact and prosumer cameras

13 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Pixel Sizes Full-frame pixels 1/3 larger than APS –More light-sensitive Existing pixel values averaged to create new pixels through interpolationinterpolation

14 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Scanning BacksScanning Backs and Studio Cameras Linear arrays used exclusivelyLinear arrays Trilinear arrays preferred to area arraysTrilinear arrays Long exposures generate heat which can cause digital noise and blooming digital noiseblooming

15 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital Image Storage Memory card flexible removable memory deviceMemory card

16 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Digital File FormatsFile Formats Files may be compressed to use less storage spacecompressed RAW TIFF (.tif)TIFF JPEG (.jpg)JPEG

17 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Removable Storage Devices Secure Digital (SD) CompactFlash (CF) –Capacities from 128 Mb–64 gigabytes (GB)gigabytes (GB) Memory Stick xD-Picture Microdrive SmartMedia Lexar/SanDisk/Fujifilm/Sony Corporation/Hitachi

18 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Storage Capacities Depends on sensor size and file type

19 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Card Speed Transfer rate from camera to card Useful for sports and action photography Cameras also possess a buffer, or internal memorybuffer

20 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Film Image Capture Evolution of film –Daguerrotype/tintype –Wet (collodion) glass platescollodion –Dry (silver bromide) glass plates –Roll film

21 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Physical Structure of Film Flexible base material Light-sensitive (emulsion) layer(s) Special-purpose layers

22 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Black-and-White Film Film base Single emulsion layer Three additional layers: –SupercoatSupercoat –Subbing layerSubbing layer –Antihalation layerAntihalation layer Surfactant used as wetting agentSurfactant

23 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Color Film Film base Three emulsion layers Five additional layers

24 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. How Light Affects Film Photons affect silver halidessilver halides –Silver bromide ionsions –Silver bromide crystals contain sensitivity speckssensitivity specks Silver clumps form latent image Negative density proportional to light Positive (print) will reverse values

25 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Characteristic Curve Relates exposure to density Different for each film First section = film base plus fogfilm base plus fog Middle-density section = straight-line sectionstraight-line section Right end = shouldershoulder

26 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Characteristic Curve (Cont.)

27 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Film SpeedFilm Speed Ratings Measurement of light-sensitivity –Lower number = less sensitive –Higher number = more sensitive Sensitivity doubles/halves with each ISO step Film grain increases with speed Based on requirements by International Standards Organization (ISO)International Standards Organization (ISO)

28 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Film Speed/Grain Relationship Grain increases along with film speed Film emulsion improvements reduce grains at high speeds –Tabular grainsTabular grains Chromogenic film produces a grainless black-and- white imageChromogenic film

29 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Reversal Film Transparency is first generation image Exposure more critical than print film Two-step development process –Negative silver image –Color dyes (positive) replace silver

30 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Negative/Positive Film Most common film type –Monochrome and color Wide range of speeds Processing readily available –Developed film is negative –Print is positive (second generation) image High-contrast lithographic filmlithographic film

31 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Instant-Print Film Film + developer –Print in 60 seconds or less –Monochrome and color Mostly replaced by digital imaging

32 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Forms of Film Cartridge film –Almost obsolete Film in cassettes –35 mm and APS –Drop-in loadingDrop-in loading –Lighttight cassette protects film –Film loader requiredFilm loader

33 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Forms of Film (Cont.) Roll film –Medium-format cameras –Paper backing holds/protects film Sheet film –Individual, thicker film sheets –Must be used in holders –4 5 most common today

34 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. R E V I E W Where do the similarities between traditional and digital image capture end? When the light rays reflected from the subject reach the cameras image receiver.

35 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. R E V I E W 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 B. Bayer

36 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. R E V I E W Color film may have as many as nine layers, including _____ separate emulsion layers. three

37 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. R E V I E W True or False? Photons of light striking the film emulsion form a latent image. True

38 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. R E V I E W Film with an ISO rating of 400 is ____ times more sensitive to light than an ISO 100 film. four

39 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Antihalation layer –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-size –Sensor 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Area array –A grid made up of rows and columns of electronic sensors. Bit depth –A numeric expression of the number of shades of gray a pixel is capable of displaying. Blooming –In a digital photo, the smearing or bleeding of some color pixels, especially red, into adjacent parts of the image.

41 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Buffer –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 speed –A measure of how rapidly image files can be transferred from the camera to the memory card. Characteristic curve –An S-shaped graph that serves as a snapshot of a given films reaction to light. It shows the relationship between exposure and density increase.

42 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Chromogenic film –A type of black-and-white film that produces an essentially grainless image composed of dyes, rather than silver. Collodion –A 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Color information –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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Compressed file –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 noise –Tiny light-colored spots especially noticeable in shadow areas of a scan or image capture.

45 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Digital signal –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 loading –A 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Electronic array –An arrangement of millions of tiny solid-state photo sites used to capture an image in a digital camera. File –An individual digital image that can be stored, transferred, or manipulated. File formats –Different modes of saving image data, such as JPEG or TIFF.

47 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Film –A light-sensitive, silver-based emulsion coated on a smooth, usually flexible plastic, base. Film base plus fog –The 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Film loader –A 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 speed –The films sensitivity to lightthe higher the film speed, the less light is needed to create a latent image on the emulsion.

49 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Filter decals –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. Firmware –The built-in program found in a digital camera or similar device.

50 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Full-frame print –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 levels –The distinct steps between pure white and pure black.

51 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S 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. Interpolation –In scanning or image-editing applications, the creation of new image pixels by averaging the values of the surrounding existing pixels.

52 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Ions –Atoms carrying a positive or negative electrical charge. JPEG –The 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 image –A photographic image that will not become visible until developing chemicals are used to bring it out and make it permanent.

53 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Linear array –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 film –A high-contrast material that produces an image without graduated tones. The film is either black or clear. Sometimes referred to as lith film. Memory card –A digital storage device used in cameras; available in a number of forms and a wide range of capacities.

54 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Memory Stick –A form of memory card used primarily in Sony cameras. Microdrive –A tiny hard drive the size of a CompactFlash memory card. RAW –File containing the basic image information captured by the cameras sensor and saved with a minimal processing.

55 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Scanning backs –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 specks –Impurities 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 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Shoulder –The right end, or high-density portion, of the characteristic curve, representing the highlights of a scene. Silver halide salt –A light-sensitive chemical compound used as a key ingredient of photographic emulsions. SmartMedia –An early form of removable memory card for digital cameras.

57 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Straight-line section –The middle-density portion of the characteristic curve, where the density/exposure relationship is most nearly proportional. Subbing layer –A very thin coating of pure gelatin that helps bond the emulsion to the base.

58 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S Supercoat –The very thin, tough topmost layer of the film. Its primary purpose is to protect the emulsion from abrasion during exposure and processing. Surfactant –An ingredient of the films supercoat that promotes absorption of processing chemicals to help ensure even development. Tabular grains –A thinner flatter form of silver halide grains, developed to allow an increase in film speed without a corresponding increase in visible grain.

59 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. T E C H N I C A L T E R M S TIFF –Tagged Image File Format. Trilinear array –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-Picture –Tiny memory cards, about the size of a postage stamp, used in some digital cameras. They are available in capacities of 16Mb to 2Gb.


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