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fredag 9. september 2011

Extended dynamic range using Layers from Bracketed Exposures 1.

One criticism of the 43 sensor is that it has limited dynamic range compared to mid to high end APS-C sensors. This means that highlights become white blocky areas and lose realism, and shadows the same in dark slabs. In fact the criticism is that the top of quarter tones, light with detail, and the bottom of three quarter tones actually disappear into highlight and shadow in an otherwise well exposed shot, leaving an area which is unrealistic, in being blocky, posterised or marked by noisey speckles.

In a perfect world we would have sony's sensor qualities in the D7000 in four thirds, and there will be progress in this at least within 12-14 megapixels according to many enthusiasts who know a thing or two about quantum physics.

However we want to acheive what we can within our limits or as part of the challenge of mastering our equipment and post processing (post') technique.

A simple means to capture more dynamic range is to make bracketed exposures, and then layer them onto each other. The top layer or even several layers are made partially transparent.

The best technique is to use a tripod and take three immediate shots, especially in daylight so conditions and shadows will be as near as possible between each bracketed shot. Most all enthusiasts cameras bracket on increments (+/-0.7 is a good starting point, giving three bracketed shots). Otherwise cameras often have an exposure adjust, which allows for slight under and slight over exposure to +/- one exposure step. A simpler but less effective means of doing this is without bracket function is to set the camera to aperture priority and simply take one shot "right" and two other shots either side of that. Alternatively you can as I have below, set up manual exposures which vary the depth of field as well as the overall exposure.

From the cameras own LCD /LED screen it can be difficult to judge the exposure of each shot, but you can see that some are quite dark while others become too bright. You can look at the histogram to see if there is a large skew to the last 5% of either side of the scale. However some overly dark shots on screen actually have a lot of detail to be tweaked back out of them.

So I recommend setting up with a tripod and running lots of shots: get a feel for the depth of field ( we are going to consider a long depth of field which gives a sense of "realism" in combination to extended dynamic range). The second advantage of a tripod is you can shoot unusually long exposures in daylight @f18-22 or in addition an ND or polarising filter.

Example Using Gimp

This is my next experiment, having come a long way in adjusting jpegs in curve work, sharpness and so on. It helps if you have worked in layers before, but in fact this can be the simplest use of layers (as apposed to the long route to masking to blur a background in an earlier blog).

For my first ever venture into layering for extended dynamic range, I chose some night shots with very long exposures. I wasn't happy with the end results in either of two exposures : one was too dark and the other was light and soft with flat highlights around some nice period style lamps.

I wanted to try several exposures but on the laptop I wasn't pleased with either of the two "keepers" from the back of the camera view. However both had their merits. So my first fodder for a long awaited experiment.

So what came out of the box??





One too dark: maybe a lift would help it, but then it may lose depth and realism. The other one is about right, but a bit too soft and short a depth of field. Also the highlights are overcooked around the detail lamps I wanted.

Try One: Dark onto of lighter: shining through?


Okay, so these have uploaded not so great but you can see there is a subtle extension to the DR in the merged down shot, dark ontop of light with about the right transparency (sorry I forget if it is 60% + or under 30%: experiment yourselves, use undo to get back !)

The highlights are still blown and the detail is not sharp. A kind of worst of both worlds but the exposure is better.

Now the reverse: a thin, 24% light layer ontop of a 65:8:5 sharpened dark layer which was lifted slightly in the shadows. The light layer on top is slightly dropped on the highlight peak (lamps of course)


Now! Here I have had quite a plasticy looking "dark" layer once sharpened, but the feint light layer is merged down at 24% opaicity it unexpectedly softens it nicely. The main aim was to lift the shadows.

Any benefit over just one image worked up on curve and sharpening though?? Well as mentioned the sharpening which hardened the details on the lamps, balcony, woodwork etc would be too intrusive while the image with the best DOF viz the darker, if chosen would become noisy and dull when lifted so much!!

I have heard of layers being used from negatives in the dark room, suppositioning several exposures onto one paper. And of course it is the origin of the colour process!

So I am pretty pleased and once again I feel a little of the magic that people had 30 years ago and longer when an image would appear out the baths magically.

Here is the image larger below because I can see the compression is killing the IQ : however you can see what I mean above in all the shots.

fredag 2. september 2011

Mu Ft y

Well I am disappointed that sony is going over the top in spec and price for the NEX 7 while Nikon look like following Pentax into an early grave with limited, price point competing interchangeable lens cameras.

What do I like about mFT?

Same things I like about FT- size, entusiast spec in controls and menus, expandability

Then there is : expandability..in 2020....the range of bodies, the new choice

-ve? CDAF ?? the range of new cameras...will I miss out on IR laser range finding which will be PDAF quality if i buy the flavour of next week? or built in EVF?

Sensor quality gap: will it be worth it? I mean a d7000 for 'serious' thought out shots and a ZX1 for walk around shots capable of wowing or sligjhtly impressing people on Facebook?

PRICE of decent kit. The price per f stop has to come down!

Unfortunetly Nikon isn't going APSC or a crop onto their 16mpx chips set up to say 12. They are allegedly doing a small sensor and a slow mega zoom according to the rumour mill. Bummer . Panolyeiaca will feel no pressure to do anything more than the EPM 3 and maybe an entry level from panny.

mFT is an annoying premium market: you pay more for less: slower lenses by in large, and more per f stop under f3 than FT or sony for example. They use less materials, which is probably one reason they went FT rather than APSC or of course FF . Oly would have been well served with a manual FF based on OM lenses sans autofocus as a serious pro, top am' cam'. But they struggled to make margin out the top line from the OM2 apparently and made cheaper lenses after y2.

The japanese engineers have been at it since the 1950s: compete on size-miniaturise and use mechatronics to employ less labour per part and less materials too.

For me the cash on the lenses which flatter the body is just too difficult. I mean if they had a killer 12-40 f2-2.8 and a 40-150 f3.5-4 I would be happy to buy a complete system. Then I'd have the OPTION of the 45mm f1.8, not feel the necessity for faster glass.



søndag 28. august 2011

The micro FT proff' camera?

Olympus seem to be spitting out new PEN models faster than a sausage machine so god knows how their product & project managers cope with endless change-? Panasonic too, have a fairly meteoric rate of upgrades to both G and GF cameras.

But when will there be a higher end micro four thirds camera from these two?

Olympus stole the limelight again with the faster((sub f2) fixed focal legnth lenses, then Panasonic came out with a super thin kit zoom, optimised for size and actuall HD video uptake.

Crystal Balling First over the Line

I would think Olympus will beat panny because they will coincide the launch of their pro "short" zoom, starting at 12mm and ending somewhere 40 to 60mm, f2.8-4 I dare say. They would then launch this with a pro level body if you ask me, and thus beat panasonics two "fast" 12-35 and 35-14x mm .

At this time then olympus will have the two fast primes, the walk around 14.150 and perhaps a fixed telefoto (200 f 2.8) : anyway we would expect them perhaps to make a grip extension body to be able to handle up to this size from the ZD shg range in full four thirds: remember compared to DSLR APSC and NEX lenses, these are still quite compact and fast enough for most anyone who doesn't want silicon wafer layer thin depth of field.

SO basically they will have all the lenses, and just need to decide to take on board all the e1, e3 and e5 users with a body which will take the big lenses of FT.

Form and Fucntion

In effect, if they choose this route, the camera will NOT be a PEN PRo but rather a camera between E620 and E5. THis will probably be about the size of the samsung NXs but with something special ergonomically, either out the box or with the "strap on" approach which has now reared is potentialy ugly head on the PEN EP3.

In fact though, if it is to be a pro level camera, with a value-added electronic view finder (EVF) I don't seen any need for it to be smaller than the current E520.

Wish list
14 mpx -16 mpx
better Sensor with Extended Dynamic range
10 fps std. - 20 fps @10mpx
2 CF cards, 2 SD cards
Repixilated Monotone shots to 24mpx
Inbuilt iR laser range finding / focus alternative
Enhanced CDAF
Focal range lock, focal distance display, focal bracketing
Focal target selection OLED and EVF
OLED 1 mpx ( 960,000 dots) touch screen
Multiple bracketing
In built blue tooth
Information rich, large EVF with extended functionality
In camera DR extended processing option
Curve adjustment in camera by touch dndrag
User definable programmed modes ( eg sports, bracketing etc)
Internet optimised blue tooth/3G/Wifi file transfer
RAW + thumbnail jpeg with option for "process jpeg on idle"
Battery life indicator (frames, minutes, %)
Option for powered zooms from on camera control
Light intensifying slow refresh live view and EVF for low light / night



14 mpx -16 mpx...perhaps with a G3 style extended aspect with target tracking on outside the frame

EVF ;

Instead of a high refresh rate which everyone really wants, what about a light collecting slow refresh allowing you to see a night or low light, or very high contrast scene to be able to compose the frame before you shoot.

That and instant monotone view for example, or as with the high contrast situation above, a composite shot refreshing to the extremes of the tonal curve thus fooling the eye with a hyper DR view to help compose long exposures with ND filters----for example!!

Infact you can go beyond the OVF, into showing detail the human eye can't capture TTL!!!

Also, as with sony, you can have an in EVF "spirit level" which would dfo help me anyway!


The grip extension: additional battery in built. An SSD drive with SATA cable. In build 3G and WiFi FTP, swing out side flash mount.

more on layers

Layer for extended dynamic range, colour correcion, sky/background adjustments are the next exeriment for me.

Brikk333 presents the following quick fix for a washed out sky

okay, at the risk of being too technical:

1. Duplicated the original layer, and then on top of it created a bright luminance mask (which masks out everything but the brighter areas of the photo.

2. picked a cyan/blue that seemed pleasing to my eye in terms of a blue sky, and painted over the unmasked areas.

3. That also obliterated the clouds, so on top of the painted area I added a gradient mask that removed the mask from the bottom and gradually less and less going up to the blue sky. And then on the underlying layer, in blending options, I played with the white blend if slider until it brought out all of the whte clouds.

Entire process - about 5 minutes.


søndag 21. august 2011

Work Flow: Take End Point for your Image First!

Sasuo Writes on DP Review about his Work flow and I have to question some things about this:

Firstly- in your initial run where will the image be going? These days, for me it will be facebook and the processing will be on a little super portable netbook (eventually a tablet when the software and processors are up to it).

So I would actually reduce SIZe first then work on the smaller JPEG at even VGA size: this is all you need for FB and probably flickr but even then it may get compressed further and shown in about 500x 400 maximum anyway!

Why FB , why not eleswhere? SOme of my pals are really talented photographers and everyone appreciates a nice album amongst the "brushing my teeth and mega late for work" posts. The best shots will get worked up elsewhere and to 10mpx, comparing a RAW processed image once I like the worked up jpeg at full size, just to see if there is more detail and nuances ( very rareley: Olympus has a fantastic JPEG engine built in which would be one reason for a photo journalist to get an E5 or PEN 3- no POST required!)

WHy? it is a shed load faster. However I do take the best images

Sosua writes on dpreview:

My workflow is process in lightroom, I will often shoot bracketed shots to blend for dynamic range (after years of experience with GNDs, blending is preferable for me), in lightroom I tweak:

Contrast
WB
Balance individual colour channels (awesome tool)
Lens corrections
Image rotate and crop
Noise reduction and capture sharpening

Then in CS5 (some images will go through PTGUI or exposure fusion):

Local micro contrast adjustments
Dodging and burning as required
Print sharpening and sizing as required

For the record, here are Reuters guidelines for image manipulation (not that I am a documentary journalist anyway):

http://handbook.reuters.com/...ief_Guide_to_Standards,_Photoshop_and_Captions

Interesting reading, and far more liberal than I imagined. I'm seeing more stitched images in Nat Geo these days too.

But really as Ray says, you can do anything you want if you feel it adds to the image.

After all, we are trying to communicate three dimensions, emotion, sound and smell into a two dimensional medium and the camera as a tool is inherently limited to achieve that.

I get everything right in camera, its just how I choose to develop the colour and tone of those images which is my choice, rather than an irreversible decision made by a hunk of metal, silicone and plastic

fredag 19. august 2011

Hyper on Dynamic Range

Even photography itself, in the days of degeurrotype, was a novelty and a little bit of a gimmick.

Many of the gimmicks and fawcets of cameras, films, lenses, filters and now sensors in their path of evolution have come to roost as established styles and techniques.

Probably what is the latest of the emperors-new-clothes to many luddites, is Hyper Dyanamic Range in post processing and the latest enhanced, broad dynamic range nascent in-camera, surpasing that of the human eye even. HDR is here to stay.

DR- dynamic range a measure of the extremities of light intensity which can be captured on the sensor and subsequent image file for the given exposure. This means that the nuances of light and dark extend so far as becoming pure white, or pure black shadow at a given upper and lower level of light intensity.

What is actually equally important to image quality, is tonal depth. Despite modern digital cameras proporting to have the same technical tonal depth in number of bits, different cameras render these better in RAW and in-body jpeg. Combining a wider DR with excellent TD means that more detail and nuances of colour and brightness can be captured.

How does this add up to the pretentious and contentious "IQ" ? Well you can argue a lot about subjectivity in this, but if you are a 10 - 12 mpx Four Thirds / mFT owner then you know all about limited dynamic range. Blown highlights where large blocks of white make a very intrusive presence on photos from scenes with high contrast taken on an average or subject spot exposure.

High or broad DR means you are capturing more tonal depth at the extremes of the intensity of a scene. This can now surpass the ability of the human eye, leading to a slightly surreal or jamais vu feel to especially dawn and dusk images. The additional nuances allow us to see more detail and more texture. This means the eye, sorry brain, picks up on additional qeues for depth and interest in a shot, and basically makes the perception of realism. Alternatively the surreal or the presque vu or jamais vu come through.

Okay now I am getting a little arty and subjective about how good DR and corresponding TD make for a good shot. Essentially good DR also means that more of the scene can be reported as being properly exposed or at least "pleasantly". When combining several images of different exposures as layers in post processing software, the very best of each can be employed in a final image.

Technically you can measure DR and tonal depth as finite, and DR from the various tests is often worth looking up for a camera you want to buy, and comparing to in particular the excellent DR of the Nikon D7000 and the Nikon D3S and then to rival models vying for your hard earned wonga.


But what about doing your own HDR on a four thirds camera? We want to avoid both blow highlights AND heavy shadows with in my case, the Olympus / OEM CMOS "red spotted dabs" syndrome in shadows and highlights.

Here is my next experimental path in The GIMP, starting asap, as expressed by JPMATH on flickr.

jpmatth (70 months ago | reply)


here's the entire process, simplified where possible:

* set the 20D's auto exposure bracketing to 1 stop.
* stand really still, and squeeze the shutter until three shots are taken (that would be 0, +1 stop and -1 stop). try not to move the camera (didn't have a tripod with me).
* developed each RAW file with the same settings (with recipes in DPP), and exported to highest quality jpeg (to retain the EXIF data).
* opened the three jpegs in gimp as three separate layers, with the 0 exposure at bottom, then -1 on top of that, then +1 at the top of the stack.
* moved the layers around until each element of the scene lined up as much as possible (because i was handholding, each exposure was a few pixels off from the others even though they were taken milliseconds apart)
* added transparent (black) layer masks to all but the bottom layer
* painted white on the layer masks where i wanted sections of each layer to show through.
* flattened everything and cropped the edges where the misalignment was obvious.
* a little unsharp masking to hide the slight softness of the misalignment
* saved to a final jpeg with quality at 90, no smoothing, subsampling at 1x1,1x1,1x1 and DCT method at floating point.

tirsdag 19. juli 2011

Blogg Deck Olympus E450

Time for another short BLOGGDECK of links to the E450 bloggs over the last year.

My portrait project is on hold until I join the new camera club, so this is jsut retrospective and I haven't been blogging a while.


2011 Posts


Photoshop vs Camera Skills

http://olympe450rants.blogspot.com/2011/01/sliders-curves-or-straight-out-box.html

Living within Your Boundaries on the E450

http://olympe450rants.blogspot.com/2011/01/living-with-limitations-of-olympus-e450.html

GIMP or Photoshop ?

http://olympe450rants.blogspot.com/2010/12/to-gimp-or-not-to-gimpgimp-vs-photoshop.html

Monotone is Rich

http://olympe450rants.blogspot.com/2010/11/black-and-white-and-sepia-all-over.html

Custom Settings for the Olympus E450 Part I
Custom Settings for the Olympus E450 Part II
Mini Useful Tips


Earlier Best Blogs

Spot Meter Experiments
http://olympe450rants.blogspot.com/2010/10/meter-experiments-with-olympus-e-450.html
Bracketing Exposure on the Olympus E 450

http://olympe450rants.blogspot.com/2010/10/it-all-hinges-on-bracket.html

Virtual Short Depth of Field

http://olympe450rants.blogspot.com/2010/09/photo-time-simulated-depth-of-field.html

Night time and low light Shooting with the Olympus E450
http://olympe450rants.blogspot.com/2010/09/olympus-e450-notes-night-shots-town.html
http://olympe450rants.blogspot.com/2010/10/e450-on-carrotsnight-vision.html