Name Means: High Dynamic Range Photo
Extension: .wdp, .hdp
In hopes to compete with the Jpeg and Jpeg2000 formats, Microsoft announced the HD Photo format in May 2006 (called Windows Media Photo at the time). The format promises the compression capabilities of Jpeg2000 but only require the computing power required by Jpeg. The HD Photo format also provides for Alphanumeric transparency, high dynamic-range imagery, high-bit depths, and ICC color profiles. By the looks of the specification, Microsoft appears to be aiming to create an all-encompassing image format for use in photography and web-design.
The need for a new proprietary image format is dubious at best. Many of the primary features of HD Photo are already available in other formats that do not require licensing to use. The promise of smaller file sizes and faster save times are items which are quickly becoming non-issues as well. Storage space is rapidly increasing in size and reducing in cost wile computers also become faster and cheaper.
Twice now the tech industry has had to deal with licensing issues gone south. Lawsuits over LZW compression (found in .gif) and Jpeg have cost companies tens of millions in legal fees and licensing fees. Microsoft’s format will require the industry to gamble on the chance of another series of such lawsuits.
Support for HD Photo is included in Windows Vista. Support in Windows XP is available through updates.
Update 03/10/07: Microsoft has recently announced that it will be releasing HD Photo to a standards body making this an open format. When—or if—this happens, I’ll update this entry to reflect the change.
Name Means: Joint Photographic Experts Group
Full Name: JPEG Interchange Format
Extension: jpg, .jpeg (Less commonly: jpe, .jfif, .jif)
The Jpeg file format gets its name from the form of lossy compression it uses as set by the Joint Photographic Experts Group. There is a great deal that gœs into why and what a Jpeg really is, but it’s quite complex and outside the limits of this article. If you wish to learn the technical aspects you can read the Jpeg FAQ or the Wikipedia entry on the format. What’s important to us is how it pertains to photography.
Jpegs are very popular for digital photography due to their small size. Cameras can process them quickly and they take little space to store. In the early days of digital photography (and really not that long ago), these two points were very important. They let manufacturers build cameras that could capture images at acceptable speeds without requiring customers to take out a second mortgage to pay for very expensive storage solutions. Todays cameras however are rapidly increasing in processing speed and storage solutions are relatively cheap. As a result any benefit that could once be gained by shooting Jpeg is quickly disappearing.
Furthermore, there is the issue of image quality. Every camera captures raw data despite what file format the camera is set to record to the memory card. With Jpeg the developing of that raw data is done in the camera instead of on your computer. Here lies the problem for many photographers.
The interpolation algorithms (sophisticated math designed to guess what should fill in the gaps in a raw image) needed to interpret that raw data and achieve the best results (called iterative interpolation algorithms) are much to complicated to be calculated in the camera. Cameras simply do not have enough processing power due to restrictions on cost and power consumption. Less sophisticated algorithms are used instead resulting in images with less accurate color, less detail, increased chance of moiré, increased noise and any of the other possible side effects of the Jpeg format itself (namely compression artifacts). For more on this please read about the Raw file type.
The area where the Jpeg format really shines in not in image capture, but in website output and transmission over the web. Jpegs are designed to produce just enough picture quality to fool the eye into believing it is looking at something of photographic quality yet at the same time reduce the image size as much as possible. This makes it an ideal standard for displaying images on the web.
Name Means: Portable Network Graphics
Extension: .png
In the early 1990s a series of lawsuits caused a bit of a stir in the tech industry. The lawsuits were headed by Unisys and Compuserve seeking licensing rights for LZW compression long after it had been put into wide-spread use in the GIF file format. When Unisys and Compuserve realized the GIF image format was gaining popularity on the web (and that they even owned the patents) they decided to cash in on the patents they owned. The two companies went on a lawsuit campaign and charged imaging software companies royalties for an already aging format. On June 20th, 2003 the patents expired allowing LZW to be freely used.
In 1995 the PNG format was created as an open-source and freely available format in response to the litigation. The idea behind PNG was to create a format that could replace GIF.
PNGs never took off as much as many web-developers and geeks alike had hoped. The format essentially remains “in-limbo” due to the lack of proper web-browser support from the dominant Microsoft Internet Explorer 6.x (which at the time of this writing has 95% of the web-browsing market). Internet Explorer 7.x however does offer proper PNG support and so this may change in the near future.
As it stands for photography its shortcomings keep it from being useful in any way since it was not designed to meet the needs of a photographer.
Further Reading: Official PNG Site | Wikipedia: LZW | Wikipedia: GIF
Name Means: PhotoShop Data file
Extension: .psd
The PSD is a format unique to Adobe Photoshop. It’s a specially designed lossless and proprietary format geared specifically for graphic editing. Due to the widespread use of Photoshop, many photographers and graphic artists use the format and have no reservations against archiving files using it. The use of layers and adjustment layers allow for many tonal and color edits to be made to an image without altering the original. These changes can easily be altered or reversed later on if desired.
Name Means: Unaltered (for the most part) data recorded by the camera sensor.
Extension: varies from manufacturer and camera
Typically raw files are compared to traditional film negatives. Both hold the original image at its maximum possible quality level. However this is where the comparisons generally end. A raw file is much more than any film negative ever was. While film is set in contrast, color response, tone, saturation and white balance based of what type of film you bought and how the transparency or negative was developed, a raw file is for the most part free of these restrictions. The image has yet to be “baked.”
By capturing raw data with a camera and processing it later the photographer is free to tune his/her images to their liking with far greater effect than what could ever be done with an image captured in Jpeg (or with film) and still maintain considerable amounts of the original image quality.
The raw “format” is the shooting choice of most discriminating photographers and there are a few things occurring which will certainly widen that adoption. Anymore, cameras are capable of saving raw data more easily than they used to be able to capture only Jpegs in the past. The cost of storage required to support a raw workflow is rapidly declining at incredible rates. Finally, with the release of post production software such as Apple Aperture and Adobe Lightroom, managing and working with raw is just as quick if not easier than working with Jpeg images alone.
Despite the benefits to raw there is a downside. Raw is predominately a proprietary format which changes from camera model to camera model, even from cameras of the same company. None of these proprietary raw formats are documented in a means that allow third-parties to utilize them. Raw development software depends on reverse-engineering the files. This issue leads to questionable longevity of a photographers work. For this reason Adobe created an open raw format called DNG which many companies have already adopted support for. For more information on this issue and what you can do to help change this, please read the The Raw Flaw.
Name Means: Tagged Image File Format
Extension: .tiff, .tif
The Tiff format was designed to be a extremely flexible format while also being a format for exchanging images across any platform. They accomplished this by allowing third-parties to store additional proprietary data within the image without breaking previous versions of software made to read Tiff files. The effectiveness of this varies from application to application and just what sort of proprietary data is stored in the Tiff file.
What this means for digital photography is that the Tiff format can handle just about anything we can throw at it. Color management, multiple layers, lossless compression, etc. The Tiff format is hands-down the best format for storing flat high-bit images with no loss in quality which can be opened by a majority of imaging programs on any operating system.
Name Means: Bitmap
Extension: .bmp, .dib (Device Independent Bitmap)
Technically every image format mentioned on this page is a bitmapped image (also known as raster Image). Images come in two flavors: raster or vector. A vector image is an image derived from mathematical formulas to describe shape and color and is infinitely scalable. A raster is made with pixels sorted in a grid to create an image (this is why images become blocky in appearance if you zoom in too close).
The Windows BMP is a very basic format created by Microsoft and IBM back in the early days of the graphical operating system and is the main file format used by the Windows Operating System (the Start menu button in Windows XP is a BMP file for example) and IBM’s OS/2 operating system. A BMP is uncompressed and contains no information beyond the image itself.
This format is not typically used of outside of Microsoft’s operating systems.