Dynamic-Photo HDR 4 and Halo-Matix

I promised another session with the HDR test sheets.  Here's a new sheet I designed.  It consists of some complicated black to white gradients.  Upon those I layered two articulated squares.  The first, in the upper left consists of a bottom layer of pure black followed by more layers each one brighter by 5% (the B in HSB) than the one preceeding.  The second, in the lower right, consists of a base of pure white and then additional layers; each one darker by 5% than the one underneath.  I then drew a number of pure white or black lines from one zone to the other.  Many of these lines were one line width apart.  At the place in the center lower left where the white lines and black lines come together I drew more lines in near-middle gray (136, 136, 136).  You can just barely see them.  Here's the chart:

It all looks very Piet Mondrian.  I then fed this to the HDR software which happens, in this case, to be Dynamic Photo HDR 4.  I used 'Auto Adaptive' and full HDR.  Then I used the Halo-Matix tone mapper and that produced this with default settings:

       

I tried Halo Matix because of the good separation between similar tones that it showed in the last test and here we are not disappointed.  All the dark squares are clearly separated; even the 100% and the 95% black square inside of it.  These could not be seen in the original.  The effect of the transformation has been to progressively exaggerate the lightness of the nested dark squares.  Contrariwise it has exaggerated the darkness of the nested white squares so that they, also, are separated.  The one pixel-width lines, black and white, are all much more clearly visible in this version than in the original.  If you go to the Picasa album here and enlarge the Halo-Matix version (click on 'Full Screen') you can also see some gray lines clustered just above the short black lines in the lower left center.  These gray lines are also more visible after HDR processing (particularly the vertically-oriented ones).

Now let's look at the same image when made bright and the halos increased to the maximum size:

Here the dark squares have maximum separation but the increased brightness has merged the brightest squares into each other with generally poor separation of tones - but better as they get darker.  Turning down the brightness of the image improves things as we see in the next image.  It is as dim as the settings allow but with max halo size:

The two lowest black squares blend into each other here to a much greater degree but the white squares are mostly clearly separated.  They are given a much greater range of darks.

   Now let's reduce the size of the halo setting to a minimum:

This image was produced with the brightest setting but with a minimum halo size.  Again the bright setting forces the brightest squares into each other and the small halo is clearly seen especially around the lines.  In the darkest squares each seems to run through exactly the same brightness ranges and the separation is achieved by enhancing the differences at the edges of the squares.

   Last of all comes the dim setting with minimum halo size:

One thing we notice in these low-halo settings is that they will certainly degrade tiny details that are close together.  Because each line has a halo around it these halos run together where the lines are close together and thus degrading the entire area.
   I created a chart to sum up what I think I've found and here it is:

 

If your eyes are like mine you'll have to click through to read it.  So it turns out that brightness has a relationship to tone separation for darks (bright) or lights (dim) and tonal separation can be achieved by radically altering the tones or by leaving the tones more or less the same and simply emphasizing the edges.  The chart should help you to pick the settings you need for whatever it is you're trying to achieve.  I think that for the next post I should find a desaturated image and experiment with it by trying these different settings to see what difference it makes 'in real life'.

Until next time...