File format for storage.

[ericmark]

I was taking photos of a wedding so opted to change the format from Pentax RAW (PNG) to Photoshop RAW (DNG) so they would not have a problem in the future in reading the files.

However when I came to look at the images I found the size had jumped up from just under 10M to 16M in size, and when I came to correct the images in Photoshop, there was no sidecar created, but instead it was included with the DNG file, and to return to as taken, one had to open up each picture again, not simply delete the sidecars.

Due to the increase of size I needed two DVD’s rather than one to store the pictures, and I have as a result returned to using Pentax RAW.

Since Pentax have in the past been good as far as being backwards compatible, and I can still use lenses bought in 1980 on my D-SLR, I can’t see there being a problem in the future, unlike the Canon and Nikon who seem to have changed many times.

To convert to DNG must be even worse with cameras that will not record it directly in that format. At least with my camera it will record directly in that format, so one asks, why should we use the DNG format? Especially since very few makes seem to have given the option? Maybe with other makes, as with my Pentax, it takes up so much extra card space, the manufactures have decided it’s not worth it?

For the wedding I still think I did the right thing taking in DNG format, but can’t convert back to PNG, where as if I had done the reverse, and taken in PNG, I could have converted to DNG.

So to the question. Do you think photos, which are likely to be kept for a long time should:-
a) Be taken in manufactures camera RAW and stored in that format.
b) Be taken in manufactures camera RAW and converted to DNG for storing.
c) Be taken in DNG format in camera and stored in that format.
d) Be converted into TIFF, and stored, as it’s still 16 bit, and been around for years.
e) Converted to Jpeg and stored in that mode as takes up even less room.
Of course assuming all options are available.
Although I realise there is less info in a Jpeg, I don’t have any idea as to if there is more or less information stored between TIFF, DNG, or PNG (or other manufactures format), but would guess there must be losses in the conversion. So I would have thought storing in the manufactures format is likely best option!

[Marko]

I'm not sure what prompted you to make that change....and isn't PNG just a different web file format...? I'm not familiar w/Pentax...but on my Nikon, there'es only 1 RAW format. The whole DNG thing, as far as i know is just another RAW format made by adobe...but PNG is a different beast AFAIK.

I shoot RAW 100% of the time and so do most of the pros that I personally know. There's no predicting the future but since millions of photographers currently shoot RAW native to their cameras...I expect the format (or some easy way to convert formats should the need ever arise) to be well supported for the rest of my life...

[Iguanasan]

Pentax has the ability to capture images in RAW or JPEG formats. Pentax RAW, unless I am mistaken are .PEF files and my opinion is that this is the best way to store your images for posterity at this time as it's the raw data from sensor. Converting to either PNG (Portable Network Graphics) or JPEG (Joint Photographic Experts Group) formats "throws away" information to create smaller file sizes.

Digital Negative, DNG, is a format that hasn't proven itself in my mind. The aim for the format was to provide a standard format for all RAW files as right now they are all proprietary formats. However, the effort to convert each and every image to DNG for storage is an onerous one without any real benefit.

Very long term storage of images is quite questionable at this point as who knows how long this technology will last. I have data on 5 1/4 inch floppies but no floppy drive to read the disk. So, to that end, I try to keep all my images on live media. That is I store them on hard drives and, in fact, multiple hard drives, and continue to move them each and every time the technology advances. My hope is that I will keep pace with the change and not leave any of my images in the "back closet" and leave myself in a state where I cannot get them back.

Hope this helps.

[ericmark]

You are correct it's PEF not PNG. We have a pro at the club who keeps talking about using DNG for storage so decided to change for wedding. Will not do it again will keep to Pentax RAW format.

[Barefoot]

d) TIFF, no compression. 'nuff said.

[flozaeliza]

PNG is more meant for graphics art, JPEG is better for photos.A PNG file is just as large as a DNG file, sometimes even larger
So, I always prefer JPEG format.