J takes us back to the very foundations of digital photography with none other than the, love-it or loathe-it, JPEG file format. If that seems like old hat, then step back another century to the iconic work of William Henry Jackson who produced some of the first photos of Yellowstone National Park.
JPEG is an acronym for the Joint Photographic Experts Group, which is actually a sub-group of the ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 1, or more catchily, ISO/IEC JTC 1/SC 29/WG 1! The two main standards organizations (ISO and IEC) came together in the early 1980s in order to work on digital still image file formats and are now responsible for maintaining the JPEG, JPEG2000, and JPEG-XL standards.
Digital imagery began to gain ground in the 1970s and, because of this, there was a need to add photo quality graphics to text based computer terminals, however file formats of the day were uncompressed so file sizes were large. This was at a time when hardware was slow and storage expensive. The rudimentary bit map (BMP) stored each RGB pixel value individually. This was improved with a simple compression algorithm used in Run Length Encoding (RLE) but something more sophisticated was needed for low bandwidth devices, connected by even lower bandwidth telecoms. Enter the JPEG.
The key philosophical underpinning to JPEG is to make an image visually appealing to the human eye. It takes continuous tones from a digital input, reduces them to 8-bit, before smoothing them to the point that the image appears almost indistinguishable from the original to the human eye. I say indistinguishable, but "quality" is a user controlled parameter where you can increase the compression (for smaller file sizes and faster write speeds), at the expense of image quality. As a result, this process is known as "lossy compression" because the original image data is discarded, typically achieving compression ratios of 10:1.
The JPEG codec involves compressing 8x8 windows of pixels systematically using a discrete cosine transformation (DCT). The aggressiveness of the compression is determined by how accurately the DCT replicates the original pixel values. The operation of DCTs on 8x8 blocks is why we see "blocky" artifacts in poor quality JPEG images. It is also the reason for posterization which results in pixellated transitions between blocks across smooth tonal changes. It gets worse when you re-save JPEGs as the DCT is reapplied to the already saved image, causing progressive degradation. The introduction of lossless rotation was one solution to help ease the problem.
Other than in situations where you need small file sizes, fast write speeds, or social-media ready images, the recommendation is generally to retain the raw file as this will give greater latitude in post-production. Or if you don't want to do post-production! The strength of the JPEG format is that the standards group required it's methods to be implementable without license fees. It was a good solution and free to use which consequently meant it became widely supported.
JPEG2000 was the first update to JPEG and offered mild increases in compression, but significantly greater flexibility. Ultimately it was too complex for its time. JPEG XT, published in 2015, extends the original JPEG format up to 16-bit and includes floating-point coding, lossless compression, and alpha channels. JPEGXL is at the draft stage intending to produce high levels of compression. The question remains… will we still be using TIFFs and JPEGs in 10 years time?
William Henry Jackson
Born in 1843 and living to the grand old age of 99, William Jackson epitomizes the life of the hard working settler of the American West. His love of the arts, and painting, was inspired by his mother Harriet, herself a talented water-colorist. In 1862 (aged 19) he enlisted in the Union Army, serving for 9 months and fighting in the Battle of Gettysburg. His regiment mustered out in 1863 and then in 1866 he traveled west to the frontier, arriving at the end of the line near Omaha, Nebraska. He settled in Omaha in 1867, setting up a photography business with his brother. It was during this period that he made now-famous photographs of American Indians in the surrounding regions.
In 1869 Jackson was commissioned by the Union Pacific Railway to document the scenery along the different railroads — now that sounds like one heck of a commission to me! As a result of that, he was then invited by Ferdinand Hayden to join the 1870 expedition by (what was to become) the US Geological Survey to the Yellowstone River and Rocky Mountains. As the official expedition photographer he was the first to capture images of now iconic locations which included the Grand Tetons, Old Faithful, Yellowstone more broadly, the Colorado Rockies, and Mount of the Holy Cross (he is recorded for the first ascent along with Hayden). The expeditions and their images were also instrumental in Congress establishing Yellowstone National Park in 1872, the first national park in the US. A serendipitous beginning indeed, all resulting from being a photographer in the right place at the right time, producing good results, and getting noticed.
In terms of technological process, Jackson began using the collodion wet plate process — this was a significant improvement on the Daguerrotype but was still an involved process requiring sensitization of glass plates in the field, before exposure and development. A contemporary of Jackson was John Thomson who as a travel photographer had equally demanding locations. Jackson preferred working with multiple cameras which included a stereographic camera (which was probably at the peak of its popularity), a full-plate (8x10") camera, and an even larger 18x22" plate camera. To support his role as expedition photographer he had 5 to 7 men who transported his equipment All of which makes our 35mm DSLRs seem somewhat ordinary.
He accompanied Hayden on all his expeditions through to the last in 1878 before moving to Denver, Colorado, establishing a new photographic studio. He received specific commissions in Colorado, as well as for several railroads, before the World's Transportation Commission requested he photograph transportation systems across the world for the new Field Columbian Museum in Chicago. He spent 2 years completing the project, producing a portfolio of over 900 photos that is now held at the Library of Congress.
In 1897 Jackson shifted entirely into publishing, selling his archive of 10,000 negatives to the Detroit Publishing Company (DPC) and becoming their president in 1898. The DPC printed images ranging from postcards to large panoramas across all areas of public interest, working from a catalog of 40,000 negatives and peaking at the production of 7 million prints annually. The company went into receivership in 1924 and was liquidated in 1932 with Jackson's negatives being sold to Edsel Ford, son of Henry Ford. The collection west of the Mississippi is now held by the Colorado Historical Society, with a number digitized and viewable at the University of Colorado, including his famous photo of the Mount of the Holy Cross.
Other J's that didn't make the cut this week include Sarah Jones.
A to Z Catchup
Lead image a composite courtesy of Skitterphoto and brenkee via Pixabay used under Creative Commons and Wikipedia, in the Public Domain. Body image courtesy of the Library of Congress and in the Public Domain.