An Experiment - - HDR Images

[michaellinder]

michaellinder,

 

 

I don't generally use HDR, so I'm not sure where it's most effective. In both of your shots, what is the primary point of interest? They both have great dof so my eye isn’t directed by focus/out-of-focus, the contrast is pretty even throughout both the B&W aerial shot and the wet street shot, and the colors are all about the same saturation in the street shot. I don’t know where to look in either. Help me?

 

The primary subject is the kiosk.

[michaellinder]

Im not sure what HDR is. I think someone once mentioned its layering images to increase sharpness?

 

Why not just use DOF?

 

Paul, as far as I know, hdr not only increases detail, it also brings out more fromeach end of the spectrum.

[Ed_Ingold]

It might be helpful to post a true HDR image, without processing other than conversion from a 32 bit master to a TIFF or JPEG. This is the garden scene from above. If you check the histogram, you will see that it fits tightly into the dynamic range, just touching the black and white limits. Unlike Photomatix, AuroraHD lets you save the raw HDR file if you wish to render it in another manner, or with a different template. While this image may look "normal," it has useful detail in areas not captured in any of the single frames used in its creation. It's a little bland for my taste, but some of you may prefer oatmeal to pancakes. Any Photoshop/Lightroom tools could be used, including tone-mapping.

 

[AlanKlein]

Ed, The foreground is too light compared to the sky's brightness at this time of day. It's not natural. Try darkening the shadow areas and let's see what happens then.

 

I tried darkening it but only got this far. A little better but still not right.

 

[The Shadow]

The last version Ed posted was simply what he got straight out of the camera, shooting in HDR. On page 2 of this thread, he shows the three bracketed photos that resulted from the HDR shot as well as his own workup. In that photo, which I consider the one he thinks of as his final result, the foreground shadows are deeper and the lighting more realistic to the scene and situation. The reason to shoot HDR at times is to capture as much info as possible, especially in shadowed areas, to allow one to preserve detail in shadow rather than losing all sense of depth and texture. A good post processor will retain the detail and depth in those shadows while not losing sight of the overall picture, which includes important dark—but not DEAD—areas. On that version, his contrasts and lighting seem to work. My issue is with the greens, which feel unnatural. I’m also not fond of the whitish patch in the sky just to the right of the sun’s rays peaking out from the tree.

[Ed_Ingold]

Most people think of "HDR" in terms of the end results, often exaggerating colors and patterns within the image. As I have shown, the first step is to mush a wide dynamic range (about 20 stops in this case) into oatmeal. From that point you can add brown sugar and berries to highlight various aspects of that image - season to taste, in other words. The actual HDR image is only the starting point in this endeavor.

 

The fountain, in backlight, is the focal point of the image. I chose to darken the foreground, while increasing the contrast and saturation in that part of the image, to emphasize the effect of backlighting on the red leaves, which was visually quite dramatic at the time. This provides a structural balance between light and dark, between the focal point and the foreground. Vignetting or selective darkening would not achieve the effect I was seeking. I moved enough off-center to hide the sun behind the willow tree, and create a sun star with enhanced contrast for definition.

 

My monitor is calibrated and set to 150 cd brightness. The foreground is not blocked as I see it. It is a good representation of what I print, using a Canon Pixma Pro-10.

Edited September 10, 2018 by Ed_Ingold

[Ed_Ingold]

The last version Ed posted was simply what he got straight out of the camera, shooting in HDR.

Actually, the HDR image immediately above is a composite of three bracketed images, assembled using AuroraHD, and rendered without further processing. Sony does have an HDR function, but only for JPEG results. I have never used it. However I do use a "standard" setting for DRO, or "Dynamic Range Optimization."

 

The bright sky near the sun's disc is overloaded on all three images. The only way to darken it is by artificially graying the sky in that region.

 

I may have been heavy-handed with saturation, which affected the green hedges. However the park prunes hedges and shrubs regularly with scissors, so that individual leaves remain intact. They're pretty bright green, even in person.

[Tim_Lookingbill]

Wow! Ed, that's one detailed jpeg you posted. I reached into the shadows and pulled out a lot of low noise detail in the foreground plant. If your Sony is that good, I don't see any reason to use multi-exposure stack blending. Here's my take on how it should look according to the color of dusk/dawn light.

[Ed_Ingold]

Wow! Ed, that's one detailed jpeg you posted. I reached into the shadows and pulled out a lot of low noise detail in the foreground plant. If your Sony is that good, I don't see any reason to use multi-exposure stack blending. Here's my take on how it should look according to the color of dusk/dawn light.

Thank you, but the HDR image was not from the camera alone. I used AuroraHD to combine the three, bracketed shots (0, +/-2) to create a 32 bit HDR image, then used AuroraHD to render that image as a 16-bit TIFF without applying filters or tone-mapping. I posted a PNET-sized JPEG of that TIFF file. You will notice that only the -2 stop frame held any detail of the fountain, and only the +2 frame had detail in the shadows.

 

The master HDR file can be saved as xxx.TIF.MPAUR. It can't be viewed in that format outside AuroraHD. Basically, the MPAUR format is a raw file which can be processed, non-destructively, using various templates in AuroraHD. That lets you experiment without taking time to reload the component images. I don't always save the MPAUR file, because the originals are adjacent to the master. I stack them in Lightroom to save desktop space.

 

You did a nice job rendering the HDR, losing the fluorescent greens while keeping a low-key "frame" around the fountain.

 

Hopefully, this illustrates the power of HDR and subsequent processing to capture difficult scenes, without the gaudy overkill we often see in HDR rendering. Best of all, it is very easy to take bracketed shots, with or without a tripod. Nikon DSLRs, my Leica 9-P and (naturally) the Sony A7/A9 take up to 9 bracketed shots in rapid succession with a single press of the shutter release. The most recent Sony cameras can even use the electronic shutter to produce full, 14-bit RAW images, at up to 20 fps. It is so easy, that I leave the camera in bracketing mode while traveling, only switching it off when shooting people in motion, or from a moving car. If I forget, the "0" frame can be used by itself.

 

That said, there is a slight variation between hand-held frames even at 20 fps, which must be automatically aligned in AuroraHD (or Photomatix). There's a box to check for that in each program. The edges are then cropped (automatically), which means a slight loss of size. You can avoid this by using a tripod, and a little care to minimize vibrations.

[AlanKlein]

TIm, interesting but isn't the foreground way to light for the ambient lighting? My taste is different. To me, it doesn't look natural.

[The Shadow]

I agree with Alan.

[Tim_Lookingbill]

TIm, interesting but isn't the foreground way to light for the ambient lighting? My taste is different. To me, it doesn't look natural.

I have to disagree with what you're seeing, Alan. I've been making mental notes shooting similar scenes in my local park because I tend to make those foreground shadows too dark. I also stopped adding too much clarity to distant tree detail shown to the right of the fountain spray which would always make the scene appear like a miniature diorama.

 

Distant objects should be less sharp and defined compared to foreground objects which should appear with more clarity and sharpness to amplify the appearance of depth. Dutch masters paintings knew this optical effect and used this technique in their paintings to convey depth 100's of years ago.

 

There's also the possibility that our black levels may be different between our displays. Like I indicated previously my display is calibrated and profiled and passes the black level test to where I can see a difference between 2RGB black patch against a 0RGB black field.

[Tim_Lookingbill]

There's something I need to make understood about those who think the foreground plant shadows are too light. One thing I found out about processing/editing HDR Raw images especially from high bit, high quality captures such as from the Sony is there is a TON of tonal variation captured in deep shadow detail. What this does is proportionately ramp up all other tonal detail that must become lighter. This allows point curve nodes to spread out for more discrete editing of these extra tonal levels that are obscured due to it being dark.

 

The histogram will have more of a triangle shape with a gradually tapering angle toward absolute black. I edited the jpeg in ProPhotoRGB which has a 1.8 gamma encoding representation of the histogram in ACR 6.7 (CS5) Photoshop. This also allows a more gradual tapering toward black in the shadows which creates a veiled effect that agrees with the strong back lighting provided by the background sun obscured by the tree, clouds and fountain spray and additional light provided by the sky light.

 

Images are composed of blocking of lights and darks and mid tones where the shadow of the red plant is one block shape the eye examines in relation to the other blocks of tone. The level of contrast for each block of tone should vary according to which light source is dominant as positioned in the scene. The diffused sky light adds to the veiled effect in the red plant shadow so it should show some lightness and some level of increased contrast because it is closest to the viewer.

 

The histogram for that edited jpeg has tonal levels in the shadows that go all the way to black. You just can't see it because it is in shadows but the contrast intensity should only hint at this. See the Digital Colormeter numbers taken in my browser screengrab...

[Tim_Lookingbill]

Your browser must be color managed. Forgot to add that. In some versions of Firefox it assumes sRGB as default. In other versions you have to turn it on through config something or other.

[Ed_Ingold]

I posted the HDR image in sRGB, as an 8-bit JPEG. This limits the color and bit resolution, but doesn't seem to have an especially deleterious effect on your processing. Viewing these images in a non-color-managed browser probably look best in sRGB. Posting in a broader color space like Profoto RGB or AdobeRGB (my Sony default) will have less contrast and make the dark areas appear lighter. I'm using Safari, which is color-managed.

 

It will never look "natural," because your eye can't see the fountain and foreground at the same time in real life. The dynamic range is too great without time to adjust from one part of the scene to another.

[Mary Doo]

Last night - rainy, sometimes thunderous. But crazy people like me and a few others went out to Jamestown to do night photography, It turns out there weren't a lot of interest anyway. We shot the Newport Bridge with the foreground very much boat-cluttered. I like this building - which is the merged result of 3 images plus Photoshop meddling.

Olympus EM1 II with Panasonic-Leica 8-18mm lens @11mm (22mm in 35mm format). f/4.0; varying shutter speed and ISO.

[Ed_Ingold]

Apart from a silly mistake, this video gives a clear view of how HDR capture works, and when it should be used. Photographer Tim Cooper makes a clear distinction between HDR and tone-mapping, which are usually lumped together. A +/- 2 stop bracket is four stops and five shots, not a five stop range.

 

Just because the histogram tapers off at one end of the scale, particularly the low (black) end, doesn't mean you can simply lift the shadows and get good results. Doing so usually results in high contrast, which emphasizes noise in that region. You are better off to bracket at least one stop at the low end, to bring shadows into a better range. Likewise at the opposite end, if you want to bring out texture in an overcast sky.

 

Photomatix and AuroraHD do a good job compressing the dynamic range of the bracket into a single image, without undue emphasis on the dark or bright ends of the scale. In other words, you keep the distinction between light and dark parts of the image, only with useable detail in each (q.v., the raw HDR I used as an example). AuroraHD has the distinct advantage of an option to keep the 32-bit RAW image for future processing.

 

Considering the wide dynamic range of modern digital cameras, I find a +/- 2 stop bracket works nearly all of the time. The original image has about a 4 stop margin at either end of the scale, so the bracket adds a comfort zone with better clarity at the extremes. Exceptions would include dim church interiors with stained glass, interiors with windows in daylight, where 5 stop differential might exist. A three-shot bracket is done in about 1/2 second, with only minimal changes in the framing. This is a 5 shot bracket in 1 stop increments. The scene is a lovely Irish day from inside a stone church (oratory) in Clare County.

 

[scott_eaton5]

As mentioned prior in this thread tone mapping is really doing the heavy lifting when it comes to HDR. I don't even bother with multiple exposures because with proper tone mapping technique and a really clean base image (and proper photoshop layer masking) you can get 90% there. Multiple exposures just gives you the data, and if presented in a tone range mapping to a single exposure looks pretty bland.

 

Taken to it's extreme HDR / Tone Mapping produces some crazy stuff. I use it sometimes to create 'dreamscapes' like the carnival shot and are meant to be over the top and abstract.

[scott_eaton5]

However, HDR / Tone mapping can also be used in a subtle way to increase dynamic range a bit without drawing attention. I typically use the HDR / Tone mapped image and then layer mask it with the original. A good example is the snow shot below. I used HDR / Tone mapping to bring up the shadows a bit and produce an image like my eyes saw it.

[Ed_Ingold]

According to Tim Scott's video, you don't have to bracket if the dynamic range of the scene is within the scope of a single shot. However the histogram doesn't tell the whole story. In this example, the original ("0") shot is entirely in range, but lacking in detail and color, which is brought out nicely using HDR and tone mapping. Secondly, if you are trying to bring out a little detail in fog, or an egg-shell sky, a 32 bit HDR is less likely to show banding in areas of low gradient than manipulation of a single frame.

 

Edited September 16, 2018 by Ed_Ingold

[scott_eaton5]

Works wonders with film scans as well. Color neg film in particular can lack micro detail because of it's lack of density range, and I've used tone mapping to extract 'realistic' detail from neg scans when I should have used tranny film in the first place. I'll try to find some examples.

[AlanKlein]

Ed, My screen is calibrated to sRGB. I looked at your image in IE, Chrome and Edge. They all show the green hedges to be too light for that time of day in my opinion. But if you're happy with the results, that's what counts. Everyone looks at things differently.

[Dieter Schaefer]

I am not using HDR much anymore even though I do bracket some shots that have too high a dynamic range so that I can do an HDR later. Most of the time, I rather blend the images with the different exposures into one composite.

 

This one is an example where I consider HDR essential - otherwise either the interior goes totally dark or the exterior is washed out; I've tried to keep it natural in the way I remember seeing the scene:

 

Prince of Wales Hotel - Dining Room

 

Merge of HDR processed with Aurora HDR and Photomatix. Photomatix helped me getting some more detail and brightness in the interior, Aurora HDR managed by far the better outdoor scene.

 

FWIW, on Ed's park image, I like Tim's interpretation - I feel the others are too dark in the foreground.

 

Not sure why Michael's kiosk image needed an HDR treatment - the dynamic range of the scene doesn't appear to be that wide.

[AlanKlein]

I think the examples show just how difficult HDR is to get right. In my eyes, none of them look right while some do better then others. Our eyes and brains know something is wrong if the lighting doesn't appear natural. A lighter hand is better than a heavy hand.

 

Dieter: I hope you don;t mind. But I played with your photo adding some contrast that darkened the interior but lightened the exterior while adding contrast. I think the lighting is more natural looking. What do you think?

[Dieter Schaefer]

Dieter: I hope you don;t mind. But I played with your photo adding some contrast that darkened the interior but lightened the exterior while adding contrast. I think the lighting is more natural looking. What do you think?

I don't mind at all. Subtle change - but clearly an improvement. I've done the processing a while ago and can only recall that it was time consuming and I probably at one point got fatigued and gave in. I need to go back and do it again - I haven't been exactly happy with my version as there are clearly some artifacts - in addition to the imbalance between interior and exterior lighting.