A genuine idea? Part II

In previous post I hinted at a new idea, but let me explain first what the new DNGMonochrome will offer. And yes, I know I'm going slow, promises promises, but this whole transformation was way more work than I had anticipated. I assure you it's not vaporware.


What's new

New is the user interface. Away with those small previews. You will now get the full image after conversion, able to zoom in to 800%, drag the photo around etc. Mostly based on Lightroom-like functionality.

Away with the clutter: no more noise reduction or deblurring (DNGDeblur will get a similar transformation, but you'll have to use the separate program).

Away also with the RGB filters. Nice experiment, but it came too close to true color interpolation and was dependent on white balancing, which I couldn't show, since there's no full color photo around. I'm not totally convinced though there wasn't an upside to it, so I might bring it back in a later version. Then hopefully a little bit more intuitive.

An improvement: you don't have to select RAW filters upfront anymore (you still can, but it's not necessary). If you run the conversion as three plane, you can filter in hindsight and save the photo once it looks okay to you.

Another improvement: added a histogram for the RAW result.

And a nasty one to get right, but I think I've finally got it: portrait photos are rotated properly.

What stays is the option to produce a monochrome photo without interpolating at all, by cutting away the red and blue and one of the greens. It's a very nice way to get to a small 'true' monochrome photo, without any of the interpolation artifacts (if you can live with 25% of the original size and a 50% reduction in width and height). It's also a handy option to experiment with the RAW filters, because it's all a lot faster. Then when you have the right settings, go for the full interpolated one.

New also: more algorithms. Apart from the one already in there, three new ones are added.

And of course more camera support. Most of the Leicas (M8 till M10, included the 240, 262, 262 M-D, the CL, SL, S, S2 and T), the Canons (EOS 350D, EOS 500D, EOS 550D, EOS 30D, EOS 40D, EOS 60D, EOS 5D Mark II / III), the Nikons (D200, D800, D800E) and the Sony A7s. For all the non Leicas the one condition remains: you'll have to convert the RAW (which should be a full RAW, not some smaller format = untested) to DNG first, with Adobe DNG Converter or Lightroom (export as DNG). I've also made some improvements handling the more quirky combinations of tags in a DNG, which should make it easier to add new cameras and better fulfill the promise of DNG as a universal format.


The algorithms

I have to remind you that we're pixel peeping. All the stuff discussed here needs at least 400% magnification to become visible. When it comes to algorithms, it's more nerdy and less photography. But well... when in pursuit of 'the best', it can't harm to focus on the extreme details.

VNG - Variable Number of Gradients - up til now it was the only algorithm used in DNGMonochrome and it will be fully implemented (the current one has a few tweaks that will disappear). VNG is strong on diagonals and arcs, doesn't produce excessive noise, isn't too bad when sharpening with Lightroom. Weak point: it can zipper on highlighted edges.

ACP - Adaptive Color Plane - I like ACP. It's the simplest of the four serious ones I'm implementing. It's fast, it's gritty, it's very strong on horizontal and vertical edges. Weak point: it can mess up diagonals (saw tooth like artifacts or 'jaggies'). When sharpened up it's comparable to VNG, but overall it's less soft than VNG (mind you, 400% to 800% magnification, else you won't see the difference).

AHD - Adaptive Homogeneity Directional - AHD is almost perfect. It's strong on every edge, it doesn't produce zippers, it's a little bit 'gritty', which I like. But really, there's no such thing as the perfect algorithm. Weak point: AHD can look quite nasty when you start sharpening it up in Lightroom. There are patterns everywhere. A bit maze like. And this isn't completely solved by balancing the greens (only made less apparent). The patterns gives the sharpened up photo a glazed-over look, like the image is behind broken glass. But if you do not intend to sharpen excessively or if you have a better (different) sharpener than Lightroom (or don't mind tweaking the sharpening with the masking and detail sliders), AHD is hard to beat.

LMMSE - Linear Median Mean Square Error - LMMSE is the most complex one (although AHD also has some tricks). It sharpens up very nicely and it's the least noisy one. When I read up on it I realized it was partly the implementation I had been searching for (under the theoretical assumption that the color channels should be able to 'help' reconstruct the green channel in a more profound way than the other algorithms did - I was convinced that could be a strategy, but I had no clue how). It's strong in every aspect. However, despite the fact you can't argue the results, it's my least favorite one. Regarding artifacts it's probably the best, out of the four presented in DNGMonochrome, but it looks very much like a Lightroom photo turned black and white. I think it's just a bit too smooth for my taste. No grittiness or a bit of bite. Maybe the noise gets eradicated too well. However, seeing all its strong points, don't let my opinion hold you back. Especially on high ISO photos, LMMSE might be the one best suited.

Since LMMSE is complex, I've currently only finished implementing the single plane version, so when you use LMMSE, you can't filter (yet).

For completeness and comparisons I also added bilinear, but I want to urge you not to use that one for anything serious. It's really second rate in all aspects.

On speed the order is (fastest first) measured in single plane: ACP, LMMSE, VNG. AHD is left out here, since that one can't be used in single plane mode.


Green imbalance

This has been an issue from the start. Most algorithms assume G1 and G2 in the Bayer layout are more or less the same value, or at least hold a correct value. In practice this is not the case. The divergence between G1 and G2 is a result of influence from the other channels (red or blue). This was very apparent on the Leica M8 and M9, where VNG produces highly visible maze patterns in areas where red is dominant. One of the greens on the CCD of these Leicas is clearly influenced by what's happening in the red channel. The M8 is more sensitive to this problem than the M9, but both are problematic (I recently discovered the Leica S2 suffers even more from this problem, where the S doesn't so much). By now I've improved the algorithm that tackles this problem, but that's not the whole story. This issue is quite an issue, because it's not only dependent on the camera used, but also on the algorithm used. VNG needs correction on the M8 and the M9, but in other M models - as far as I can tell - correction is hardly necessary. For AHD that's a different story. AHD causes stronger patterns - mostly visible when sharpening - on all the Leica models, when G1 and G2 are too far apart (probably also on the Canons, but I haven't tested the full set yet). The problem here is that it's hard to find the right amount of correction, since it's unclear per sensor under what conditions the greens diverge most or where in the photo the algorithm suffers most from the divergence (shadows, highlights, mid tones, certain colors etc). So the new DNGMonochrome will contain a special module, where this stuff can be set and changed per camera and per algorithm. It's set already by me to some defaults I think are okay, but since my testing is limited to only a few photos per camera, I can't fully judge every situation in which these problems might show. Of course, this undercuts the whole idea that 50% of the photo stays the green as recorded. That percentage drops once you start correcting one of the greens. On the other hand: the recorded value wasn't correct to start with. The recorded green wasn't what really hit the sensor at that spot, which makes the whole point slightly moot.


A genuine idea?

So, I was going back and forth between these algorithms, being frustrated about parts of some photos working better with algorithm A, when I thought the total photo looked better with algorithm B or C, when it suddenly dawned on me: why can't we interpolate photos with more than one algorithm? Why is it a choice upfront and then you're stuck with it for the total photo? Let alone programs like Lightroom, that don't want to bother you at all with this stuff and don't even give you a choice upfront (or 'at all').

Well... I can think up a few reasons why. Good reasons.

But not good enough reasons to hold back my nerdy brain waves.

So I decided to do it.

Yes.

In the new DNGMonochrome you can interpolate one DNG (the same DNG) with all the provided algorithms.

Different parts can be interpolated differently.

Now, don't tell me that's not a genuine idea!

I will elaborate in a next post.


When is it finally ready?

Well, I'm currently finishing up on testing all the algorithms with the different cameras. All the new stuff has to work with every DNG that's supported. Especially the rotating and the possibility to interpolate different parts of the photo differently can give unexpected results with different cameras. There's still quite a few bugs to kill, so I can't give an exact date. But I hope to be releasing the official 1.0.0 before the end of November (2018). I might release an unstable bèta before that. It's not a promise though, so don't hold me to it.

Hiroshima

Hiroshima Peace Memorial - or A-Bomb Dome (原爆ドーム Genbaku Dōmu) in the evening...

It's ground zero. The bomb exploded more or less above this building. What was left standing of it was preserved as a reminder. If you visit the museum and look through the monument there, you can see this building, across the canal. It's all designed on a straight line: the museum, the monument, the square, the eternal flame... on a line extending all the way to this building: its stark image captured within the monument on the square. It was impressive, to walk around there, to notice how much thought was put into remembering and to see how Hiroshima has reinvented itself after total destruction, incorporating that gruesome event into daily life and into a powerful 'never again'.

It's a lovely city, surrounded by mountains, with friendly people, beautiful parks, nice restaurants and a unique history.

2 November 2017

Hiroshima, Japan

A Genuine Idea?

Where DNGMonochrome is concerned, I think there are some solutions out there now, which can do the same. I'm not even sure if it wasn't already possible to interpolate on just the green channel, when I came up with the idea. I seldom have a genuine idea. I might think I have, but usually I'm proven wrong later on, because I don't like to research my brain waves. I just want to act on them (if they don't involve physical action). Who cares if it already exists!

You might know the feeling.

So, for the next idea, you tell me if it's genuine or not.

What bothered me about DNGMonochrome was the interpolation algorithm. If you followed my struggles from the beginning, you know I experimented a lot with different approaches. All basically under the assumption that it should be easier to just interpolate for monochrome, than it is for color. That assumption turned out to be quite untrue. So indeed: you might not have to bother with false colors, purple fringing or chromatic aberrations as much, but some of this stuff does show up in other shapes or forms to spoil your black & white photo.

There's the maze pattern if the greens are out of balance; there's zipper artifacts on certain algorithms; there's mazing on other algorithms; there's strange patterns that would show up as moire in the color version... but moire we recognize... some weird block pattern in a black and white photo, not really.

Note by the way that all the babble following, is based on 400% to 800% enlargements. The artifacts I'm talking about are not visible at 100% or when you're just flipping through your DNGMonochromed photo album. This is about extreme pixel peeping and has little to do with photography.

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In the current version of DNGMonochrome I finally settled on VNG for the interpolation. VNG (Variable Number of Gradients) produces overall very nice results, especially strong on diagonals and arcs, and it sharpens up quite nicely, but it has at least one flaw: it can produce zipper artifacts on horizontal and/or vertical edges.

And the problem is: you can't really tweak these things (the interpolation algorithms I mean). The more sophisticated algorithms - and even the simpler ones - are usually structured around tight mathematics. A lot of thought was put into them. Just simply changing a bit here or there, or adding a bit there and here, will only lead to a lot of wasted time and frustration (you thought you solved your zippers, only to discover a major mess somewhere else in the same photo - due to your handy work).

What also bothered me was the user interface of DNGMonochrome. Small previews, not a lot of room to navigate, no zooming. That badly needed an improvement.

And I think I overdid it a bit with the denoising and the deblurring and the RGB filters. Loaded it up with too much stuff no one is actually going to use. So that's gone in the coming update (DNGDeblur will also get an update, later on, so you can still deblur the monochrome results).

It's going to be a clean interface, built around a smooth viewer that can zoom up to 800%. And yes of course finally all the new Leica cameras that produce DNGs will be supported (the 262, the 262 M-D, the M10, and maybe some of the new non-M models).

On a side note: I traded in the Leica M-A. I loved the camera and the all mechanical approach, really, but staying abroad for prolonged periods of time and traveling in between, film photography turned out to be non maintainable (or at least a huge bother). It was hard to find film and even harder to have it developed and you have to count per role how often it goes through an airport scanner. For a short holiday fine. In countries where the broken Fuji development machines are staring at you, as a sad reminder of happier days, being pointed at by the store owner - no sorry, no more spare parts: not so much. I switched to the Leica M-D. Almost the same magical experience: click and then you have to wait... but without the additional hassle.

So, I went to work and tried to improve DNGMonochrome. And along the way I got an idea, when I was implementing a few new algorithms (the new DNGMonochrome will give you a choice out of at least four: VNG, AHD, LMMSE and ACP, perhaps more later on).

A bit silly and a bit nerdy (the idea). Probably quite useless. Not fully worked out yet (it's working but I still need to inspect the end result in comparisons). But that's exactly how I like my ideas, because that might mean the idea is genuine!

I will explain the idea in a next post, where I will also try to explain the differences between the algorithms in the new version.

It's been too long

Hey there, dear reader...

I would not be surprised if there is no one left. It's been too long yes, I know. Life, circumstances, obligations, etc. We all know how that works.

Just a quick update to let you all (or probably no one) know I'm still alive and kicking.

Working on a new program and on two upgrades (DNGMonochrome and DNGDeblur are getting a major overhaul).

So if no one is interested, keep an eye on this blog!