Adobe expands DNG format with Lossy DNG

Adobe DNGYou may have heard about recent updates to Adobe Camera Raw and Lightroom, now it is time for Adobe DNG file format. If you haven’t heard about DNG, have a look at Adobe website for more information.

Adobe has extended the specifications of DNG format. Now you will be able to create a compact, lossy DNG as well.

Including lossy DNG is probably the biggest new change to DNG format, which according to Tom Hogarty from Adobe goes between Raw and JPEG. As Tom Hogarty says:

‘If you look at the output of a [Canon EOS] 5D Mark II, its Raw files are about 25MB, while its JPEGs are about 6MB. The difference in quality and capability between the two is significant enough that many photographers are happy to put up with the additional demands of the larger files.’

‘Lossy DNG allows something in-between the two in terms of size but retains the flexibility in terms of adjusting White Balance and preserving detail,’ he explains: ‘For example, the out-takes from a wedding shoot, that the photographer is unlikely to ever be able to sell or make any money from. This gives them a way of reducing the amount of storage space they need, but they still have the file if they do ever need it.’

‘It’s based on standard JPEG compression. What’s lost is some of the range of the adjustments you can make – if a file is four or five stops underexposed, you’ll find it’s not quite as flexible as the full file. You can still do a lot, though and it’s only in extreme case that you might notice.’ he says.

The compression in the Lossy DNG is set fixed, however you can reduce the pixel size of the file when you create a Lossy DNG, giving what Adobe is calling DNG Proxies.

Version 1.4 of DNG specification includes some of the new things like:

– the ability to record details of a crop that should be applied to the Raw data,

– files can include 32-bit floating-point data, allowing them to retain all the information from multiple Raw files combined as part of an HDR process,

– the ability to include undefined (or transparent) pixels, such as the non-image areas around a merger panorama.

These changes come from Adobe looking into the future and as Tom Hogarty says:

‘It’s where the industry is going. No cameras or software yet offer this, but we can imagine them wanting to.’

If you want to find out more about new features in the DNG 1.4 specification, have a look at Adobe website.


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