Digital image and file formats

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  • 1. Digital -M.V.Ramachandran

2. Digital Camera Digital Cameras convert analog into digitalinformation Represented by ones and zeros, or bits 3. Whats the difference between a digital camera and a regular film camera? 4. Whats the difference between a digital camera and a regular film camera? Film cameras depend on chemical andmechanical processes Film cameras do not even need electricity Digital Cameras have a built in computerwhich record images electronically 5. Digital camera and a Regular film camera A Digital Cameras has differentlenses that help focus the lightto create the images A 35 mm camera would focusthe light onto a piece of film. a Digital Cameras focus thelight onto a semi-conductordevice that records the lightelectronically A computer breaks this info down into digital data 6. What breaks down the infointo digital data? A sensor converts the light intoelectrical charges Digital Cameras use CCDs (ChargedCouple Devices) or CMOS(Complementary Metal OxideSemiconductor) Both convert light into electrons Value is read of each cell in the image Both operate similarly converting the lightinto readable form 7. CCD CMOS Although numerous differences existbetween the two sensors, They both play the same role in thecamera -- they turn light into electricity. To understand how a digital cameraworks, you can think of them as nearlyidentical devices. 8. Whats the real difference Because each pixel on a CMOS CCD sensors create high-sensor has several transistors quality, low-noise images.located next to it, the lightsensitivity of a CMOS chip islower. CMOS sensors are generally more CMOS sensors traditionally susceptible to noise.consume little power. CCD sensors have been CCDs, on the other hand, use a mass produced for aprocess that consumes lots oflonger period of time, sopower. they are more mature. CCDs consume as much as100 times more power than an They tend to have higherequivalent CMOS sensor.quality pixels, and more of them. 9. What else is important in aDigital Cameras? Resolution The amount of detail that the camera cancapture and it is measured in pixels. The more pixels a camera has, the moredetail it can capture and the larger pictures canbe without becoming blurry or "grainy." 10. Common Resolutions 256x256 - Found on very cheap cameras, this resolution is so low that the picturequality is almost always unacceptable. This is 65,000 total pixels. 640x480 - This is the low end on most "real" cameras. This resolution is ideal for e-mailing pictures or posting pictures on a Web site. 1216x912 - This is a "megapixel" image size -- 1,109,000 total pixels -- good forprinting pictures. 1600x1200 - With almost 2 million total pixels, this is "high resolution." You can printa 4x5 inch print taken at this resolution with the same quality that you would getfrom a photo lab. 2240x1680 - Found on 4 megapixel cameras -- the current standard -- this allowseven larger printed photos, with good quality for prints up to 16x20 inches. 4064x2704 - A top-of-the-line digital camera with 11.1 megapixels takes pictures atthis resolution. At this setting, you can create 13.5x9 inch prints with no loss ofpicture quality. 11. Types of Digital Camera 12. Digital Image Recording 13. How do Digital Cameras capture color? Photosets are blind Photosites only keep track of the totalintensity of light that strikes the surface To get full color of an image, most sensorsuse filtering to look at the light in its threeprimary colors All three colors get recorded and combinedto create the full spectrum 14. Exposure & Focus Digital camera has to control the amountof light that reaches the sensor. The two components it uses to do this, theaperture and shutter speed, and are alsopresent on conventional cameras. 15. Exposure & Focus Aperture: The size of the opening in thecamera. The aperture is automatic in most digital cameras, butsome allow manual adjustment to give professionalsand hobbyists more control over the final image. Shutter speed: The amount of time that lightcan pass through the aperture. Unlike film, the light sensor in a digital camera can bereset electronically, so digital cameras have a digitalshutter. 16. Exposure & Focus Aperture and shutter speed work together tocapture the right amount of light needed tomake a good image The camera also adjusts the lenses to controlhow the light is focused on the sensor. Most Digital Cameras use auto focus lenses 17. Focal Length This is the biggest differencebetween a digital camera and aregular conventional camera So what is focal length The distance between the lens and the surface of the sensor This determines the magnification (zoom) Increasing the focal length increases the zoom / magnification and vice versa 18. Digital Camera Lenses Fixed-focus, fixed-zoom lenses - Theseare the kinds of lenses on disposable andinexpensive film cameras -- inexpensiveand great for snapshots, but fairly limited. 19. Digital Camera Lenses Optical-zoom lenses with automatic focus -Similar to the lens on a video camcorder, thesehave "wide" and "telephoto" options andautomatic focus. The camera may or may not support manualfocus. These actually change the focal length ofthe lens rather than just magnifying theinformation that hits the sensor. 20. Digital Camera Lenses Replaceable lens systems - These aresimilar to the replaceable lenses on a35mm camera. Some digital cameras canuse 35mm camera lenses. 21. Storage Early generations of digital cameras hadfixed storage inside the camera. You needed to connect the camera directlyto a computer with cables to transfer theimages. 22. Storage Todays cameras are capable ofconnecting through serial, parallel, SCSI,USB or FireWire connections They usually also use some sort ofremovable storage device. 23. Storage Removable storage devices include: Floppy disks Hard disks, or microdrives Writeable CDs and DVDs 24. File Format Jpeg TIFF RAW 25. JPEG 26. JPEG 27. RAW 28. TIFF 29. Resolution Quality of the pictures on a screen, print, orfile DPI = dots per inch (printer) PPI = pixels per inch (screen) More resolution means higher file size Different file types contain more or lessinformation (resolution) 30. Understanding pixels Picture elements (dots) per inch Standard monitor displays 640 by 480 pixels 640 by 480 1024 by 768 More pixels requires more RAM, which maymean lower bit depth 31. Enlarging with pixels 32. Thanks