Nuts and Bolts of Digital Imaging Chapter 1 Nuts and Bolts of Digital Imaging

Resolution = Information Given a digital image of a certain size, the more pixels it has, the higher its resolution. pixel = picture element 1 mega pixels = 1 million pixels One measure of the visual detail contained in a digital image In general, the more mega pixels a digital image has, the more detail it contain.

Example (640x480=307,200 pixels)

Example 5610x3627 = 20 mega pixels

Where Resolution Comes into Play (Discussion) Camera resolution Do you know your camera’s resolution? How does it compare to your mobile phones? Monitor resolution Do you know the resolution of your camera’s monitor? How does it compare to your mobile phones? How about your laptop/ipad/tablet? Printer resolution Any ideas on the resolution of the printers you use?

Bit Depth Bit depth--also called pixel depth or colour depth--measures how much colour information is available to display or print each pixel in an image. Greater bit depth (more bits of information per pixel) means more available colours and more accurate colour representation in the digital image. For example, a pixel with a bit depth of 1 has two possible values: black and white. A pixel with a bit depth of 8 has 28, or 256, possible values.

Bit Depth 8-bit 4-bit 1-bit

8 Bit vs. 16 Bit 8 bit gives 256 (28) tonal values It is likely that your digital cameras record images using 8-bit in the JPEG format. More expensive digital cameras allow you to save images using 12/14/16-bit in the RAW file format. (example)

Colour Modes Grayscale (Black and white) RGB (Red, Green, Blue) Most common for digital photography CMYK (Cyan, Magenta, Yellow, blacK) Most common for (digital) printing Lab Reference colour space for conversion

RGB vs. CMYK

File Formats JPEG TIFF RAW Photoshop PSD Convenient, compression, lossy TIFF Lossless, large files RAW Proprietary (e.g. Canon’s CRW, Nikon’s NEF) Large files High bit-depth (e.g. 14-bit, 3 channels) Photoshop PSD

JPEG Quality