I decided to do a comparison of the photo formats. I ran two different scenarios, one on a sunny day and one on an overcast day. The DNG results were the best in both cases. All of the JPGs were so close it really would have been up to the photographer which would be the best format to use. Here's some of my notes of what I found during the comparison:
- Two sets of photos were taken (cloudy day & sunny day), using a tripod, Image Stabilization was set to OFF, and the 2 second delay timer was used. I compared the size of DNGs to the those obtained using the parameters of the "Extra Photo Operations" / "Quality Override" (Superfine, Fine, Normal, Off):
sunny day % of DNG overcast day % of DNG
------------- ----------- ----------------- -----------
DNG 18,255 KB 18,255 KB
Superfine 5,522 KB 30% 4,938 KB 27%
Fine 3,209 KB 18% 2,836 KB 16%
Normal 1,373 KB 8% 1,134 KB 6%
Off 3,206 KB 18% 2,833 KB 16%
- This was only two sets of photos so I'm not certain if the size variances will be typical.
- DNG is the only RAW format I work with, so this is the only RAW format I used in this sequence. Although there is less EXIF info in the DNGs than a typical JPG, it is adequate and the DNG can be processed directly in the applications I routinely use (Photoshop CS3, ACDSee v3 and Picasa v3).
- "Extra Photo Operations" / "Quality Override" EXIF info can be verified using ExifPro. Unfortunately the CHDK DNG is not yet fully supported - still appears pixilated, however the EXIF info is present and readable. The JPG EXIF "Quality Override" info does not appear in my copies of ACDSee v3, Picasa v3 or Photoshop CS3. So far this is the only app I have tried that was capable of verifiing this particular EXIF info.
- I wasn't able to find documentation on the "Quality Override" parameters - perhaps someone can point me to a link with the documentation? However, I checked the parameters using ExifPro and found the following results for the "Extra Photo Operations" / "Quality Override" parameters:
Superfine - Exif info indicates Superfine (5,522 KB)
Fine - Exif info indicates Fine (3,209 KB)
Normal - Exif info indicates Normal (1,373 KB)
Off - Exif info indicates Fine (3,206 KB)
<--- interesting From this I would presume if you want to use the "native" Canon format you would set the "Extra Photo Operations" / "Quality Override" parameter to "Normal" (see next posting for clarification)
Update: I had mentioned that ExifPro was the only app I had found recently that could read the Quality Exif info but that it could not display the DNG files yet. After checking IrfanView (freeware) again, I realized that IrfanView can read the Quality Exif info
AND display the CHDK DNG files. (
http://www.irfanview.com/)
