Modern Photography/Digital image formats

Digital image formats are an important part of modern photography. Regardless of whether you are shooting in digital or analog, it's highly likely that any successful image will eventually be published digitally. In addition, virtually all modern printing now relies upon digital inputs, which means that printing a book or poster-scale reproduction of an analog photograph will necessitate digitization before printing can proceed. When shooting digital, however, our camera stores the image in a digital format from the moment of capture, so our photographs are tied to digital image formats from their very inception. Let's take a closer look at what that means for our images.

Fundamentals

There are two types of digital images: bitmap (also known as raster) and vector.

Bitmap images are those in which the image is divided in to tiny squares (known as pixels), each of which has color information associated. You cannot 'zoom in' past the available data in a bitmap image, they are thus said to be of a limited or fixed resolution.

By contrast, vector images are those in which mathematical formulae are stored to define the shapes within an image. Vector images can be zoomed infinitely, are are thus not bound to a particular resolution.

Note that it is possible to convert a bitmap image to a vector image with some accuracy and contortion, this process is sometimes known as 'tracing'. Inversely, it is easy to convert a vector image to a bitmap image at a particular resolution, this process is known as rendering or rasterizing.

Because bitmap images match the sensor mechanism in most photographic equipment and are extremely widely used, bitmap images are almost always the appropriate choice for the storage of photographs, and will be assumed throughout the rest of this document.

Quality vs. Quantity

• Resolution
• Raw vs. JPEG
• Lossy vs. non-lossy

Color depth

• Examples from black and white through simple GIF to HDRI

Metadata

• GPS
• Rights
• Timestamp
• Camera and lens information
• Colorspace
• Print resolution
• Other examples

Portability

• Platform considerations
• Commercial versus open source software

Long term accessibility

• Archival concerns