A customer walked into my shop last week and complained, “ My camera isn’t working. I think there is something wrong with the chip.” Did that mean the camera’s main computer wasn’t working? Or maybe she was referring to the memory card, (the small storage hard-drive inserted into the camera)? As it was, the camera was fine and the problem was with the lens.
We should not be critical or frustrated with the owner. Since the introduction of digital cameras we have been confronted with new terminology and those new words can be bewildering.
Digital cameras have been available for well over a decade with Kodak introducing its 1.3 megapixel camera in a professional Nikon body in 1991, and then the Kodak DC40 for general consumers in 1995. Both Nikon and Canon had introduced several serious DSLRs by 2002.
Yet, all these years later, many photographers are still perplexed at the new jargon, and I will admit that sometimes I catch myself mixing up definitions or going to the internet in search of clarification. After dealing with the confused customer, and a thoughtful explanation by a friend regarding my own confusion on “bit depth,” I thought I’d offer the following help to readers.
Digital Images: The digital image is a grid of dots or picture elements (pixels). Each pixel is assigned tonal values (black, white, shades of gray, and colour). The bits are then interpreted, read by the computer, and produced as an analog version for display or printing.
Pixel: Picture Element: Digital photographs are comprised of thousands, or millions of them; they are the building blocks of a digital photo.
Sensors: When a picture is taken, the sensor is struck by light coming through the camera’s lens. Each of the tiny pixels that make up the sensor converts the light into electrons. The number of electrons, usually described as the pixel’s accumulated charge, is measured and then converted to a digital value.
DPI: Dots Per Inch is a measurement of the resolution of a digital photo or digital device. When printing, the higher the number the greater the print quality.
Image Resolution: Is the number of pixels in a digital photo and that affects the image quality.
Bit Depth: A bit is the smallest unit of data. 8 bits comprise a byte. A byte (or 8 bits) can therefore represent 256 different colours. Here is a good discussion on understanding bit depth by Ian Lyons. Go to: http://www.luminous-landscape.com/tutorials/bit-depth.shtml.
Megabyte (MB): A measurement of data storage equal to 1024 kilobytes (KB).
Mega Pixel: Equal to one million pixels.
LCD: Liquid Crystal Display: A low-power monitor used on a digital camera to display settings or the photo itself.
Histogram: A graphic representation available on the LCD, of the range of tones from dark to light in a photo.
ISO: International Standards Organization is a rating describing the sensitivity of the camera’s sensor to light.
JPEG: A standard for compressing image data developed by the Joint Photographic Experts Group. It is referred to as a “lossy” format, meaning image quality is lost in achieving JPEG’s high compression rates or when resaving.
RAW: Is the image format data as it comes directly off the sensor, with no in-camera processing.
White Balance: Refers to the relative intensity of colours in your image. Without correction, a picture taken at sunset can seem too yellow or orange, and a picture taken under fluorescent lights might seem too green.
Noise: Pixels in your digital image that were misinterpreted, usually at the higher ISO values. It appears as random groups of red, green or blue pixels.
Shutter Lag: The time between pressing the shutter and actually capturing the image. This is due to the camera having to calculate the exposure, set the white balance, and focus the lens. It is usually a problem with small point and shoot cameras.
sRGB: A colour space produced by HP and Microsoft. Although sRGB has a small range of tones and colours, it is versatile and supported by all cameras and image viewing software. The best choice for those that prefer keeping things simple and avoiding colour shift problems during editing or sharing.
Adobe RGB (1998): Created by Adobe for colour management in their Photoshop software. Because of the wide use of Photoshop this colour space is popular and extensively supported. This is a wider colour space than sRGB. It encompasses around 50% of all visible colours, and is a good choice for editing because it typically carries more information for custom printing.
Be sure to let me know if I have missed anything. I really like everyone’s comments.
My website is at www.enmanscamera.com