Digital Photography File Formats (….and why use one or the other…) Instructor: David King

Capture Formats Most DSLR Cameras (and some others) Can Capture the following file formats…  JPEG (Usually with several “qualities” or compression ratios)  RAW  TIFF Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - TIFF TIFF stands for… Tagged Image File Format TIFF Files are…  Processed in the camera  Uncompressed  Large Files  8-Bit Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH BIT DEPTH is an important quality issue. IT is SO important, it warrants some discussion… It controls how many tones and colors you can capture. It refers to how many “Bits” are required to address a given pixel’s data. This requires some background… Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH Digital Images are an assembly of numbers… … LOTS & LOTS of numbers Because the computer only knows “On” and “Off” the numbers are recorded in “Binary” format. Binary is a numbering system where only 1” and “0” are used. Each occurrence of either a 1 or 0 is called a “Bit” Each Pixel receives a number based on the signal strength that is recorded as a binary number. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH The number of bits determines the number of possible values. One Bit systems use only… one bit. It is either a 1 or 0. If 0 = black and 1 = white, then the system can only have white or black with nothing in between. Digital Photography File Formats Instructor: David King SDCC Photo Program 1 0

Capture Formats – BIT DEPTH The number of bits determines the number of possible values. A Two Bit system uses 2 bits per number. …It is either a 00, 01, 10, or 11. The Two Bit system can therefore have 4 shades from black to white. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH The most common camera capture bit depth is 8-bits. With 8-bits the system can record 256 increments from black to white. This would be to The increments would be labeled as The mid point, 128 is binary A lighter gray, 176 is binary Since each color channel (RGB) can have 256 increments, the total color permutations is 256 x 256 x 256 or about 16.7 million. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH Is 8-Bits enough? The human eye blurs increments into a smooth gradation at about 250 increments. Editing can destroy or overlap increments resulting in loss of color or tone that is discernable. Are there any better options? Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH The camera Captures 12 Bits per channel With 12 bits the camera’s system can capture a binary number of This is equal to 4095 increments per channel. Almost twice the number required for the human eye to blend a gradual tone. It allows more editing before discernible loss x 4095 x 4095 = 68.6 Trillion colors The camera can process back to 8 bit or up to 16 bits Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats – BIT DEPTH 16 Bits per channel With 16 bits the system can record a binary number of This is equal to 65,535 increments per channel. 65,535 x 65,535 x 65,535 = over 121 trillion colors You can do serious editing without losing any discernible tones or colors. You have more subtle variations of colors available for use. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - TIFF Returning to TIFF for a moment…  Remember: a TIFF file is uncompressed …  But it is processed by the camera into an 8-bit image.  But it is also the largest file type in terms of storage use.  Not all cameras record in this format.  OK, on to other formats for comparisons… Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - JPEG Almost all cameras can record JPEG formats JPEG means “Joint Photographics Expert Group” It was created for file transfer and display on computers and over the World Wide Web. It is preferable to GIF files for photo images. It is fully processed in camera based on camera settings. It is an 8-bit format. The files are small to store and fast to transfer Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - JPEG JPEG Compression is a “Lossy” type of compression algorithm. It samples and averages blocks of pixels based on the compression ratio set. Minimum is about 4:1 JPEG compresses upon file ‘saving’ so will recompress when a file has been opened and re- saved. On a computer screen, most humans cannot detect a 10:1 compression of an un-enlarged image. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - JPEG Recompressing an already 4:1 compressed image results in a 16:1 compression. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - JPEG How big a deal is the compression issue? Let’s see…  Here is a grayscale block of pixels… Digital Photography File Formats Instructor: David King SDCC Photo Program UncompressedJPEG Compression

Capture Formats - JPEG How big a deal is the compression issue? Here is a color image at various levels of JPEG compression.  REMEMBER: You are seeing this on a 72 ppi monitor not a high resolution print. Digital Photography File Formats Instructor: David King SDCC Photo Program © Wikipedia JPEG with Maximum Quality JPEG with Medium Quality JPEG with Low Quality

Capture Formats - RAW RAW is not a specific format it is a type Different manufacturers have different RAW formats. For example…  Nikon uses NEF  Canon uses CR2 and CRW  Olympus uses ORF,  And there are DCR, X3F, RAF, SRF, MRW, and now DNG RAW files contain the instruction set from the camera settings but do not apply them to the files so they are considered as being “Unprocessed” 12 Bit images. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats - RAW RAW files contain additional DATA about the image and capture Metadata* (data about the data)  This is data about the file properties itself plus search data EXIF* (or Ex changeable I mage F ile)  This is data about the Camera and Settings IPTC (or I nternational P ress T elecommunications C ouncil)  This is copyright and captioning data.  It can be added in converters or editing apps GPS ( G lobal P ositioning S atelittes)  This is location and navigational data Digital Photography File Formats Instructor: David King SDCC Photo Program * NOTE: This data is also captured with TIFF and JPEG formats

Capture Formats - RAW RAW files are like Digital Negatives They must be processed to apply or modify the camera settings They must be converted to a format useable by the image editor. Sounds like a lot of extra work… They provide the greatest creative control of the image data. Provide the only path to 16 bit processing. Digital Photography File Formats Instructor: David King SDCC Photo Program

Capture Formats Digital Photography File Formats Instructor: David King SDCC Photo Program QUESTIONS?