Compressed Digital Photo File Formats - Storing Digital Photos
Digital photos are stored as files on memory cards and computer hard disks. They can be stored in different file formats (each format has a unique file extension). Most of the formats are compressed to save space and each has its own pros and cons.
The need for standard file formats
Digital photos are saved as digital files on electronic media. These digital photo files are a collection of bytes. If each manufacturer and camera would have used a proprietary file format then you would have needed proprietary software that could read, print and display those formats. Using a standard format allows any camera to save photos while any other software can read, display and print them.
What is compression and why it is needed
A digital photo is a collection of pixels each pixel is stored as a value that represents its color and intensity. Usually each pixel is represented by an RGB value (three numbers one byte each with values 0 to 255 representing the intensity of Red, Green and Blue that combined together create the pixel's color). An RGB value occupies 3 bytes. So how big is a digital photo file? It depends on the number of pixels in the photo. For example if you shoot a photo using an 8 mega pixels digital camera the photo will have 8000000 pixels each one occupying 3 bytes. The total file size would be 8000000*3=24000000 or 24Mbytes. This is a very big file. Big files are harder to manipulate they take a long time to send by email, they occupy large storage space and they take longer to load.
In any digital photo there is data that is either redundant or that if removed the viewer would not be able to notice the difference. In addition representing pixels as RGB values is not efficient in terms of storage space. The process of compression takes advantage of these facts. When you compress a digital photo the compression software represents pixels in a more efficient way, removes redundant data and removes data that is "not important". The result is a significantly smaller file. For example the above 24Mbytes file could easily be compressed to about 3Mbytes with hardly any noticeable quality degradation.
Before compressed digital photo files can be viewed or printed they need to be decompressed. Decompression is the reverse process of compression - a compressed file is converted to its original format usually a simple RGB pixel file. Using standard compression file formats allows one software to compress a digital photo file and another software to decompress it and process it.
Lossy or Lossless compression?
There are two main types of compression software: lossy and lossless. Here are the differences:
Lossless compression is usually applied to text and other data where all data is equally important. For example when compressing the text in this article and later on decompressing it you would want to get the exact original article without any words or sentences dropped by the compression software that decided they were not important.
Lossy compression is usually applied to digital photos and graphic files. Such files include data that the viewer would not be able to notice if removed. For example small changes to color in a photo might not be noticeable. The decompressed file is not exactly the same as the original one but when viewing both the original and decompressed photos side by side the viewer can not tell the difference. Lossy compression software can be set to different compression levels based on how much data is allowed to be lost. At some point losing too much data is noticeable and degrades the digital photo quality. Many digital cameras allow you to set the level of compression from low to high where high compression means smaller files but less quality and low compression means bigger files but no noticeable quality degradation.
Common digital photo file formats
You can know what a digital photo file format is by checking its extension. Usually the extension is three letters representing a specific format. Here is a list of the common extensions and formats:
BMP Windows Bitmap: this is a basic raw format. The photo is stored as a pixel raster and is not compressed. While this format is very easy to use and is supported by practically all software it is not efficient as there is no compression applied.
GIF Graphics Interchange Format: An old file format initiated by CompuServe. It uses a lossless LZW compression and is thus more efficient than BMP files. GIF files are very efficient for storing basic graphics (that include lines, circles and other graphical shapes) and also efficient for storing small digital photos but are rarely used to store large digital photos as there are more efficient formats for that purpose. GIF files can also include multiple "frames" and support basic animation.
PNG Portable Network Graphics: This relatively new format was designed to be used in online applications such as web pages. It uses a lossless compression. The original goal of the PNG format was to replace GIF (due to some licensing complications associated with the GIF format). PNG is commonly used now by online web sites to represent small digital photos or graphics replacing the GIF format.
JPEG Joint Photographic Experts Group: Also known as JPG this file format was designed by a special industry group and became an ISO standard. The design goal of the format was the efficient storage of digital photographic files. Although JPG files can support lossless compression they are almost always used in lossy compression mode. JPG files are very efficient in compressing digital photos. The JPG compression software can be set to different compression levels with higher compression levels the photo files can get very small but they can also get distorted. JPG files are the most common ones used by digital cameras to store compressed digital photos on memory cards and computer hard disks as they result in small file sizes and hardly any noticeable photo quality degradation.
About the Author
This article can be reprinted and used as long as the resource box including the backlink is included. You can find more information on digital photo printing and photography in general on printrates.com - a site dedicated to digital photo printing Ziv Haparnas writes about practical technology and science issues.
News in brief
Here are a selection of brief news items from this week’s paper edition, and possibly a few news briefs that didn’t make it in the paper.
 |
 Free Shipping To US 8GB 8G Memory Slim 18 LCD TFT MP3 MP4 Radio FM Player BJ8G  US $16.00 |  USED Good Casio GzOne Brigade C741 Verizon Rugged Phone US $119.95 |
 Broken cracked screen Ipod Touch 4th generation US $66.00 |  Cadillac CTS Performance WE SHIP ANYWHERE IN THE USA FOR ONLY $35000 US $45,500.00 |
 Saturn Sky Red Line WE SHIP ANYWHERE IN THE USA FOR ONLY $35000 US $25,887.00 |  43 LCD 32GB MP4 MP5 PSP PMP Video Game Player Camera Game AV Cable PSP Black US $.02 |
 NEW 43 LCD 32GB MP4 MP5 PMP Video Game Player Camera Game AV Cable PSP Black US $.02 |  Nikon D70 60 MP Digital SLR Camera Black Kit w AF S DX 18 70mm Lens US $400.00 |
 HTC Droid Eris Verizon Phone 5MP Camera Wi Fi Bluetooth Black Good Condition US $51.00 |  Mercedes Benz GL Class GL320 2007 MERCEDES BENZ GL320 CDI NAVIGATION 3RD ROW SEAT HARMAN KARDON US $19,700.00 |
 MINT HTC DROID ERIS VERIZON WIRELESS GPS WIFI ANDROID CAMERA CELL PHONE US $69.95 |  Maylong M 250 2GB Wi Fi 7in Tablet Black With Leather Travel Case USB Keyboard US $104.99 |
 NEW 7 inch CAR GPS NAVIGATION FM MP3 MP4 TOUCH 4GB MAP US $38.99 |  Porsche Cayman Base LEATHER ONE OWNER CLEAN CARFAX TRADES WELCOME FINANCING AVAIL US $30,000.00 |
 Ipod 8gb US $30.00 |  Jeep Wrangler Unlimited Sa UNLIMITED SAHARA NAV HEATED SEATS DUAL TOPS AUTO TINTS R SUBWOOFER LOADED US $28,995.00 |
 Sony Walkman E Series NWZ E353 Digital Media 4GB MP3 Video Player w FM Tuner US $49.96 |  Infiniti G Base LEATHER NAV SUNROOF CUSTOM RIMS TRADES WELCOME US $10,100.00 |
 Vintage Apollo Slide and Photo Negative Viewer NEW NIB New in Box US $19.99 |  Chevrolet Camaro 2SS Automatic RS package Low miles Shipping $350 US $30,000.00 |
 Apple iPod touch 4th Generation Black 32 GB Latest Model Used US $140.00 |  Chevrolet Corvette SHIPPING ONLY 35000 IN THE LOWER 48 STATES US $33,900.00 |
 SAMSUNG SGH I607 BLACKJACK phone NO RESERVE US $1.00 |  Lexus LX 4WD 4dr LX570 Clean Loaded 4WD US $54,995.00 |
 Toyota Land Cruiser 4dr 4WD Land Cruiser Loaded Clean 4WD US $18,995.00 |  Toyota Land Cruiser 4dr 4WD Land Cruiser Loaded Clean 4WD 22 TRD Wheels US $45,995.00 |
 Apple iPod touch 4th Generation Black 8 GB Latest Model includes skullcandy US $170.00 |  Toyota Land Cruiser 4dr 4WD NEW DEMO LAND CRUISER 2013 LOADED US $78,765.00 |
 BlackBerry 9900 Bold ATT US $227.50 |  Adobe Photoshop Elements 9 US $16.59 |
| Powered by phpBay Pro |
 | Archerfish Solo Wireless Intelligent Video Surveillance System with Built-In DVR List Price:  |
DescriptionOnly Archerfish gives you powerful Homeland Security technology that leapfrogs motion detection. Smart enough to differentiate between people, vehicles and random motion, the Archerfish AFCAG04S1 Solo Wireless IP Camera analyzes what it sees and sends video alerts when important things happen... |
 | Sungale CD352LD 3.5-Inch Desk Lamp Digital Photo Frame (Red) List Price: |
DescriptionSungale CD352LD Desk Lamp CD352LD-Red 785 |
 | Satechi Cyclone Micro 2+ HDMI 1080p Portable Media (MKV, AVI, MOV) Player Adapter with SD/SDHC Memory, USB Slot and Remote Control List Price: |
DescriptionSatechi Cyclone Micro 2+ is a USB2.0 1080p HDMI Media Player Adapter with qualitative performance and advanced technology. With the Cyclone Micro 2+ Adapter you can just plug and play with any USB storage device and play your favorite media files directly to a TV via HDMI or composite (yellow / red / white phono) port... |
 | Veho VFS-002m Slide & Negative Scanner for 35mm & 110 Instamatic Negatives List Price: |
DescriptionThe new VFS-002M is Mac compatible and comes with 35mm & 110mm slide and negative trays. Convert your old memories onto your PC ready for achieving, restoring or printing. Features 35 & 110 Negs & Slides Quick one touch scan Windows & Mac compatible |
 | SanDisk SDDR-88-A15 8-in-1 USB 2.0 Hi-speed Reader (Retail Package) List Price: |
DescriptionThe ImageMate 12-in-1 Card Reader/Writer is a Hi-Speed USB 2.0 Multi-card Reader/Writer that connects to your computer's USB 2.0 port. USB 2.0 provides superior performance to transfer pictures, music, video and data between flash memory cards and your computer... |
 | Carson Z-pix Digital Zoom Microscope List Price: |
DescriptionThe Carson Optical zPix is a powerful digital zoom microscope that displays a magnified image right on your computer screen. Impressive 35x-165X magnification allows you to see details of ordinary objects you never knew existed, and you can additionally capture images with an onboard 640-by-480 resolution digital camera... |
 | Fisher-Price iXL 6-in-1 Learning System (Silver) List Price: |
DescriptionThe iXL 6 in 1 Learning System by Fisher Price is the ultimate and coolest handheld learning system designed for kids 3-7.The iXL Learning System has six great applications for kids: Digital Book Reader, Game Player, Digital Art Book, MP3 Music Player, Notepad and Photo Viewer... |
 | Lowepro APEX PV AW (Arctic Blue) List Price: |
DescriptionThe Apex PV AW pouch is lightweight, rugged and designed to withstand the elements. The convenient, single-compartment design accommodates a photo viewer or similarly sized digital storage device, memory card and additional batteries... |
MemoryKick Instructions
