Even formats that superficially appear to be straightforward can contain many separate pieces of information. Let’s take a look at the contents of some interesting formats.
Here’s a Canon CR2 file courtesy of www.rawsamples.ch. Within it there is a main image, a full-size thumbnail, as well as a small thumbnail, and some metadata.
We’ve used our Bevara Access software application to extract and decode these pieces. The main image is scaled to fit the page, but is not color-corrected; Bevara leaves color correction options open to the user.
Here’s another example, a Leica DNG image courtesy of www.rawsamples.ch. We see that it has a main image (again scaled to fit the page, but with no post-processing or color correction) and a small thumbnail.
As with many DNGs, this image also has metadata, some of which is:
Camera: Leica M8
DNG Version: 188.8.131.52
ISO speed: 160
Shutter: 11.3 sec
Focal length: 50.0 mm
Embedded ICC profile: no
Number of raw images: 1
Thumb size: 320 x 240
Full size: 3920 x 2638
Image size: 3920 x 2638
Output size: 3920 x 2638
Raw colors: 3
Filter pattern: RG/B
Daylight multipliers: 2.097456 0.946061 1.128163
Camera multipliers: 2.104980 1.000000 1.255310 0.000000
However, much of this metadata is contained in a MakerNote EXIF as opposed to other metadata storage options such as general tags and XMP; in future posts we’ll discuss internal metadata storage options. However, this range of options raises a challenge in retrieving and preserving the embedded metadata when preserving DNG-format images. If you’re relying on an asset management system that normalizes and migrates formats, you need to ensure that it takes into account any internal metadata forms as well as thumbnail versions that you need to preserve. Alternatively, Bevara’s preservation solution keeps all file pieces intact and simply packages the original data file with an accessor — read our white paper to learn more about our patented preservation process.