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Title: Exposure, Histograms & Noise - A Test Post by: Terry-M on June 16, 2014, 08:35:19 AM The recent upgrades to Qimage Ultimate where noise reduction has been improved and the related data is shown in the raw refine screen prompted me to do a little test. Here are the results:
I took some photos of some items in a dark corner in my office at the highest ISO available on my camera, 12800. I used this very high iso to exaggerate the effects and make it visible on the small attached images. The first exposure was with zero exposure compensation, the second with plus 1-1/3rd stops increase to move the camera histogram to the right. See attached images below. "Under exposed", QU pushed 12800 iso to 43460 with 10/10 noise reduction for Grain & Chroma "Increased Exposure", QU pushed 12800 iso to 17940, with 10/10 Grain and Chroma noise reduction. You can see the difference that "increased" exposure makes to the noise results in the processed image; one is poor, the other useable. I hope this is helpful to some of you, to improve technique to get the best quality from your camera and QU. ;) Terry PS. I obtained the camera histogram from the jpeg extracted from the raw. The raw histogram is, of course, modified by QU Title: Re: Exposure, Histograms & Noise - A Test Post by: tonygamble on June 16, 2014, 09:16:05 AM Here are two similar shots.
The first was at 6400 ISO. QU pushes it to 24,420 The second was at 6400 with an increase of 1.7 EV. QU pushes it to 8,320. No filters and no tinkering with the RAW. Sorry - they don't look so different here, but they are before posting. Title: Re: Exposure, Histograms & Noise - A Test Post by: Terry-M on June 16, 2014, 09:54:48 AM Going back to my original post:
Quote "Under exposed", QU pushed 12800 iso to 43460 Here is the QU histogram for the underexposed image attached.It's easy to see where the "ISO push" has occurred when compared to the camera histogram (also shown again). Terry Title: Re: Exposure, Histograms & Noise - A Test Post by: tonygamble on October 30, 2014, 09:33:09 AM I'm bumping this thread as Luminous Landscape have just posted this article on 'exposure'.
http://www.luminous-landscape.com/essays/the_optimum_digital_exposure.shtml I am not sure I'd want to spend 99 USD on the book but the article makes an interesting read. I shot a whole bundle of pix last night, in artificial light, and made sure I had a blinky on the viewfinder screen each time. I have yet to look at them in QU - but I'll come back with some comments on what I found when I do. Always something new to think about..... Tony Title: Re: Exposure, Histograms & Noise - A Test Post by: Mack on October 30, 2014, 12:18:36 PM QU has a histogram in it? ???
Maybe a Printogram? Mack Title: Re: Exposure, Histograms & Noise - A Test Post by: Terry-M on October 30, 2014, 01:36:21 PM Quote QU has a histogram in it? Huh It certainly has; never underestimate QU ;)It's in the image editor, Levels tab. See screen shot below. re. Quote I'm bumping this thread as Luminous Landscape have just posted this article on 'exposure'. After a quick look, there's nothing new there but always good to read this sort of stuff as a reminder.Terry Title: Re: Exposure, Histograms & Noise - A Test Post by: tonygamble on October 30, 2014, 03:31:24 PM always good to read this sort of stuff as a reminder.
Indeed and what interested me were the images of the rabbit and the black cat at what he called the Optimum setting. See those in a viewfinder and you'd regard the as unrecoverable - or I would have done anyway. Just been through last night's shots albeit quickly. It is interesting how many of the 12000 plus ASA ones are quite useable when you chuck enough exposure at them. Doubling the ASA so one can double the shutter speed seems to increase the keepers. Tony |