I would love to see a professionally produced maybee crowd funded
Post by BC RiderI've been playing with patch sizes for the Munki and I thought some
people might be interested in the results.
I tested mostly on plain paper. I generated a 156 patch target using
default targen values. I then edited the ti1 file to create sections of
identical colors (10 patches long). I did this four times in the file. I
then printed the target using the NON-random layout. I tested a range of
sizes from 6mm up to 13.7mm (CM -h setting). I did multiple targets with
multiple scans and compared results using the verify tool and direct
inspection in Excel.
1) I found Argyll poor at detecting row contamination (i.e. width). I
saw degradation in Excel long before Argyll flagged errors. Staggered
layout (i.e. CM layout) improved detection performance over non-staggered
layout (i.e. i1pro layout) but still not good.
8.2mm and 13.7mm are "magic" numbers that allow the target rows to be
perfect gridlines for the ruler. The ability to simply lay the ruler down
on the gridline without guesswork AND the fact the Munki is self-centering
under these conditions is very significant. All other widths require
some estimation increasing the risk of misalignment (unless one uses an
extra alignment spacer with the ruler - e.g. 10mm patches would require a
temporary 5.5mm spacer inserted which is removed when scanning).
2) Patch length issues are better detected in Argyll. However I noticed
minor degradation in quality as one approached the maximum scanning
speed. I also noticed some quality issues at extremely slow scanning
speeds (i.e. 20 seconds or more per line). This happened regardless of
patch size. Best results seemed to be scanning between half and
two-thirds the maximum scanning speed. Overall I found anything from about
8mm and longer worked fine. There is no practical difference in quality
and the scanning speeds are all reasonable.
3) Some (very few) patch sequences had issues with patch detection using
smaller spacers so I settled on 1mm spacers in all scenarios. I also
noticed randomized targets were much more tolerant of small spacers. In
fact spacers may not even be needed on randomized targets but I didn't
investigate this further.
4) Sometimes there were one or two data points with dE errors
disconnected from the group. Very occasionally a truly wild data point
occurs. This happens regardless of patch size. Rescanning the patch brings
these back in line.
Because Argyll is insensitive to row contamination, I would use a
ruler for the CM -h setting and smaller patch sizes. For truly "mindless"
scanning constraining BOTH sides of the Munki is highly recommended. I've
attached a small photo showing the idea. An aluminum meter-stick cut in
half and glued to spacers (use the Munki to set the spacing) is simple
and effective.
Given the proper scanning guide, 8.2mm seems a good general choice for
patch width. In my tests, I didn't see any benefits when using larger
widths. I also found the double-sided guide generated very robust
alignment and tracking.
Without checking the measured data one can unknowingly build profiles with
bad data. This seems to be true regardless of patch size. So I scan each
target twice and compare results using the Verify tool and, if necessary,
rescan offending lines. I then average the two files prior to making the
profile (using Average tool).
BOTTOMLINE: Everyone's needs are different so there probably isn't
a perfect target. For general use, I chose the CM target layout because
it has staggered patches and when scaled down to 8.2mm width the 8.4mm
length works fine for me. The downside of the CM layout is a tremendous
amount of wasted white space at the beginning and end of each row. I have
to mess about in my image editor to remove the extra space.
The i1pro layout is not bad if scaled to 8.2mm width. Some may prefer
the longer length. I can see why people use it. But I find the patch
length longer than necessary and prefer a staggered layout. On the
upside, the i1pro layout doesn't waste nearly as much space at the start
and end of each row so is a better choice for those wanting to avoid the
image editor hassle.
Overall the Munki seems more capable and versatile than most devices.
I've scanned from about 50 patches to 800 patches on a single Letter sized
sheet. IMO, all scenarios are perfectly valid under the given
circumstances. This versatility is a unique strength of the Munki so it
would be nice to see the Munki better supported in Argyll. To that
1) Allow scaling patch width and length separately,
2) Allow setting the white space at the beginning/end of each row
(perhaps specify minimum mm required?)
3) Option to not print strip indexing and/or allow font size scaling
Advanced users could then tailor either the i1pro or Munki layouts to suit
virtually any need.