I agree with you about saving camera images in a high bit format (16-bit TIFF or RAW/DNG), but I am not so certain that a JPG is by default in a sRGB colorspace. I think the color is defined by the sensor used to record it and the colorspace attached to the file which is often something like ProPhoto RGB or Adobe RGB. Cheap cameras may save in the sRGB format, but that is not a JPG restriction to my knowledge. Images are often converted to sRGB when they are prepared for web presentation, since web browsers will default to sRGB display it they do not find a colorspace profile in the image. And software may assume the colorspace is sRGB if there is no profile attached.
For all you folk using Photoshop with default settings, the RGB colorspace default is sRGB, unless you have identified an untagged image as being in some other colorspace when you open it. So in preferences you should probably change the RGB colorspace to default to Adobe RGB, and set the program to ask for a colorspace identification if one is not already attached to an image. 9/10 times an untagged image will be in the sRGB colorspace, so you just select that option. Then look at the results. If the colors seem unusually dull or unusually brilliant (check the reds!), you know you need to go back and pick a different colorspace. Second most likely choice would be Adobe RGB colorspace. Beyond that it would be a real guessing game that would require you to talk to the originator of the image or use your experience to select other likely spaces.
SO, always attach a colorspace profile when saving, for images you want used in production or archiving. And if file size is a concern (for web presentation) you can convert to the sRGB colorspace and save a copy without a color profile, since by default browsers will guess sRGB as the right colorspace. The smallest file sizes are achieved with something like Photoshop’s Export/Save for Web tool which strips out all the extra goo-gah adobe stuffs into normally saved files.
PS, you can save JPG files in the CMYK colorspace, though there may be fewer programs that will properly recognize it (definitely attach a profile to those!)
A jpeg (even if full quality) is always in sRGB (the colour space of the cheapest CRT monitor in the 80s) and 8-bit, which can cause problems when printing or displaying graduated tones. I had a guy printing beautiful jpegs beside me in a workshop and he was getting horrible bands in his skies. I always save my photos as 16-bit TIFs in Adobe RGB.
It will not help you quality-wise to just convert to DNG, though that has become a standard for image archiving. If you were interested in editing the photos before archiving them, then converting to a higher bit rate format like DNG might make sense. A full quality JPG image is lossless and the equivalent of saving as a TIFF. I think there are programs, as Geoff mentions that can batch convert to DNG.
Don't think that would work, MaryBeth. I just tried opening a jpg in Pshop and saving it as a DNG. Not an option. You would not be adding to the detail or other data even if it were possible.
When you say "data loss problem," what exactly is it that you mean? One can save jpegs at 100%, e.g., no content loss. Or save them as PDFs, which would also save without content loss. The question you need to ask is how were the jpegs originally saved, with or without compression. JPEGS are the least volume in your storage devices also, so it would seem best to simply save them with no compression loss. Depending of course on the size of storage drive.....and your backup storage drive.
On Thu, Jul 30, 2020 at 6:41 PM MaryBeth Hinrichs <[log in to unmask]> wrote:
Has anyone done this: changed from jpeg to camera raw or dng format? Can this be done to batches of photos? I'm very interested in doing so because of the data loss problem with jpegs; we are archiving a ton of photos right now.
Nobleboro, Maine, USA
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