G9: Sky at ISO 800

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In a previous post, I noted that I was placing some large images in a Smugmug gallery for purposes of comparison. Those first images were taken at ISO 100, 400 and 800. Both the in-camera JPEG and a raw image file were posted. A subtle difference for those first six shots of the sky is that all were slightly underexposed. The last two shots (#7 and #8) were made “just right” by increasing the exposure by +2/3 stop as compared to the evaluative metering mode of the G9. Now to examine an ISO 800 “just right” image and compare the noise to the slightly underexposed variation.

The image above is the ISO 800 in-camera JPEG that was underexposed by 1 stop in the bracketing process. This means it was actually underexposed by 1-2/3 stops in comparison to the "correct" exposure.

The images to be compared are the new Smugmug images #9, 10, 11, 12. These are the bracketed versions (+/- 1 stop) of images #5 and 6. Image #9 and 10 are the in-camera JPEGs and images #11 and 12 are the processed raw versions of #9 and 10 respectively. In particular, notice that image #12 has much less noise that image #11 and even less noise than image #6. The apparent reduction in noise is actually because much less noise is generated when the exposure is correct. In fact, this was the entire purpose of this little exercise: Minimize noise by avoiding underexposure.

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G9: Large, comparative samples

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There are many and fierce debates about the relative merits and faults of cameras and processing. Although the debate rages on, I've almost given up because the basis of the debates is so subjective. On the other hand, there is a real difficulty in making comparisons. What is the final output of the "photograph"? A snapshot sized print? An enlargement -- 8x10? Larger? Will the photo only be seen from a computer screen? How large is that screen? Is the screen calibrated for proper color, brightness and contrast? No wonder so many people have such diverging views -- not to mention justification of their expense in obtaining that camera!

For the G9 and many other small sensor digicams, one of the major issues is noise at high ISO. The G9 applies its own noise reduction algorithm to its in-camera JPEG but other noise reduction software is readily available. In particular, some G9'ers, myself included, usually shoot in raw mode and apply noise reduction afterward. Which method is best? Does it matter? Can a G9 high ISO be saved?

To systematically investigate the various high ISO and processing options, I thought to post some full size images for comparison. These will be posted on a special SmugMug gallery. The first set of images is a simple set of shots at the sky. These images were taken at ISO 100, 400 and 800. The G9 was set for raw+jpeg so the images are in pairs. When the G9 is set for raw+jpeg, the jpeg is full size but a little more compression is used. I know this confuses the issue somewhat but I made additional comparisons (unposted) and the differences between the G9 "fine" and "superfine" images are small. As it is, this set of comparisons includes eight images and there's no real point to adding more.

My intent was to simply point the G9 at the sky and fire away on Av mode. Then I decided to throw in exposure bracketing so I added a polarizing filter to keep exposures within range. Even so, the G9 neutral density filter was necessary for the ISO 400 and 800 shots. So the first two shots (ISO 100) are without the ND filter, the ISO 400 and 800 are with the ND filter. All of these shots are slightly underexposed.

The exposure was increased by +2/3 stop for a final set of shots. Of course, I forgot to remove the ND filter for these so the exposure is much longer than expected.

The in-camera jpegs were all done at "normal" settings. The raw files were converted in ACR and followed with noise reduction using Noiseware. Noiseware was used at its default settings. The raw files were all done semi-automatically using the ACR auto toning (exposure) and a Photoshop Action.

In comparing these samples, the general idea is not so much which exposure, contrast, saturation, etc is preferable to you personally as it is to see that there are, or can be, differences. Don't even bother to tell me that you can process the in-camera jpeg to have the same saturation and contrast as the processed raw image. Also, don't bother to tell me that the in-camera settings can be adjusted for more or less saturation, sharpness and contrast. But do notice that the first three conversions from raw have quite different look from the first three jpegs. This difference is largely due to the initial underexposure. These are comparisons of the in-camera auto processing of underexposure to the ACR auto processing of underexposure.

In the last two images, the G9 exposure setting was 'corrected' by adding 2/3 stop compensation. The in-camera jpeg and the auto process raw are much more similar.

Examine the files, pixel peek, print your own, order from SmugMug -- whatever you prefer. There's something or other to be learned here and it is different for all of us.
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Still More Variations on Bright Sky Processing

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In what could easily become a never-ending presentation on variations in post processing, I’ll call it quits after this one. Previously, the scenario was that only one auto-exposure shot was taken of a scene with bright sky but dark foreground. The challenge was to get the best final image from either JPEG or RAW with simple post processing. Next, let’s consider a bit more involved post processing.



Show above are comparisons of the images made with a graduated neutral density filter (Image 4) from the first posting, a Photoshop simulation of a graduated neutral density filter (Image 11) and a Photoshop blend of two “exposures” (Image 12). Images 11 and 12 were made from the same raw file – only one real exposure – but processed twice in Adobe Camera Raw (ACR).

Image 11 was made from a raw file processed first with -1/2 stop of “exposure” (for the best sky) and then again with +1 stop of exposure (for the best tree/ground); this created two image files. In Photoshop CS3, the sky exposure (-1/2) was placed as a layer on top of the ground exposure (+1). The sky layer was then blended into the ground layer by using a graduated layer mask. There are many references and tutorials on this technique. Here are some links:

Sharon Lowe
Digital Camera Magazine
Luminous Landscape

A more involved variation on these ideas is shown on the Luminous Landscape – one of my favorite photo sites. Image 12 above was made with that blending process but simplified by using Fred Miranda’s DRI Pro plugin for Photoshop. First, using ACR, two variations on exposure, + ½ stop and – ½ stop, were made from the same raw file and then saved. These two variations were loaded into DRI Pro.

Of course, you can use two or more real exposures instead of simulating exposure variations in Photoshop. Image 13, below, was made from two real exposures, +1 and -1, using DRI Pro. And then, there’s High Dynamic Range (HDR) …




High Dynamic Range is a computer based method of combining several exposures to increase the tonal range. Some like HDR and some do not; in fact, sometimes I like HDR and sometimes not. HDR images can be a bit over-the-top according to the final processing -- the “tone mapping”. There are a number of HDR software packages available. I usually use Photomatix and/or the HDR features contained in Photoshop CS3. Some of my favorite images are HDR based.

Both Image 14 and 15 above were made from three exposures at -1, 0, +1 using Photomatix. For Image 14, tone mapping was done using the default settings – a somewhat gentle and conservative approach. Image 15 was done using a more aggressive tone mapping approach.

Of the infinite possibilities, I’ve shown 13 variations on the theme of photographing and processing images for scenes having a bright sky but dark foreground. The interesting aspect of all this is that each of these methods has a place and that someone – but not everyone – will prefer one method instead of the others. But then, that’s photography and photographers!
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More Variations of Bright Sky Processing

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Returning to tips and tricks about photographing scenes with bright sky but dark foreground after a bit of PowerShot news, here are more variations on processing. The scenario is that only one shot was taken and it was based on the G9 autoexposure setting for the full composition.




In the above comparison, Photos 3 and 7 are repeated from the previous posting. Photo 8 is similar to Photo 6 from the previous posting except that it was given additional recovery, saturation sharpening. I made Photo 8 because, after reviewing the previous posting, it seemed that there was an incorrect impression given about processing from raw. Therefore, Photo 8 is intentionally somewhat overdone with respect to saturation and sharpening.

Of course, the in-camera jpg can be processed in Photoshop. That is, suppose you took Photo 3 as an in-camera jpg only. On reviewing the photos later, you realize that there is little detail in the sky and that the trees are dark. You’d want to improve the photo and this is certainly possible, as shown below.



Photo 10 was made from Photo 3 with post processing in Photoshop CS3. Only two processes were applied: 1) “Exposure” was reduced by ¼ stop and 2) Shadow/Highlight recovery was applied rather heavily. These are both simple image adjustment settings in CS3 and took only a few minutes of tinkering. These adjustments were made to the original file which was then downsized and sharpened for web viewing. No other adjustments were made to get this nice “save” with Photoshop.

Although I almost always use Adobe Camera Raw (ACR), there are other programs for converting from raw to jpg. I regularly use BreezeBrowser to view and select images. BreezeBrowser also can do some editing and can now process G9 raw images. My understanding is that BreezeBrowser uses the DCRaw program for raw conversions. Photo 9 was converted, downsized and sharpened entirely in BreezeBrowser.

My favorite is still raw plus a polarizing filter and processed in ACR but I’ll grant that the differences are not so apparent in these web sized images. Also, it is important to realize that saturation, contrast and sharpening can be further fine-tuned for any of the photos shown.

All images shown so far have been shot and processed as “single shots” with no dual processing. Next, multiple exposures will be merged.
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