Using DNG File conversion to maintain control over Image Library Size

Out of more than 110,000 photos in our image library nearly 8,600 are Camera RAW files (NEF, CR2, DCR, RAF primarily). Although they make up less than 8% of the total number of files, they account for more than 12% of the total space taken up on the drive (68 gigabytes out of 526 gigs of space occupied by the library).

The challenge is how to preserve the integrity and optimize the size of the library, reduce the multiple file formats and standardize the image files, while acquiring the best quality images for use over the coming years.

Camera RAW files are the obvious answer but the file space these would require prohibit our organization from using RAW files.

Adobe's DNG file format system is widely touted as achieving smaller RAW files while protecting the integrity of the image data -- unlike with jpgs.

Moreover, DNG files also combine the metadata into the image itself unlike RAW files which use the sidecar method of storing xmp information, and the problem with sidecar files is you risk loss of that data if the sidecar file becomes separated from the image file.

Recently I undertook a series of in-house tests using 30 random camera RAW images from a variety of different RAW formats. Bridge's built-in DNG converter made the process simple and easy.

Results:

Orig RAW: 30 images (238.5 mb)
DNG convert: 30 images (181.8 mb) - with no loss of information

Moreover, the DNGs open up just like a camera RAW file in PS CS4.

Several options are now available:

All contract photographers would be required to send the "keeper" RAW files on disk, and we convert to JPG for uploading to the library (thus keeping the library at a reasonable size). If a larger, more robust copy of that image is needed, the metadata in the JPG will direct the designers to the specific disk where they can find the RAW file. (Professional digital photographers shoot predominantly in Camera RAW in any event.)

Another scenario would be to request that all contract photographers convert their final images to DNG instead of jpg before sending them to us. This would require no additional steps on their part, since they convert the images to something after color correcting, reviewing, etc. And we get the added benefit of the BEST quality image. Of course, the photographer could send us the RAW files and we can convert in-house. With Adobe's PS and Bridge the process is quick and easy, and we can even add our own metadata information during the conversion process.

Lastly, the photographer could send us BOTH the RAW and JPG files, since DSLRs today are capable of shooting images in both formats at the same time. No conversion is needed -- however this does not take into account those files that were color-corrected.