*From*: Craig Ringer <craig@xxxxxxxxxxxxxxxxxxxxx>*To*: argyllcms@xxxxxxxxxxxxx*Date*: Sat, 29 Aug 2009 18:28:21 +0800

Hi folks I have a fairly large (2310) sample chart set I've scanned in with my i1Pro. The chart set was run off an offset litho press so I have quite a few copies. I've scanned in a few copies and I'm seeing significant differences between copies when I use the `verify' tool to compare the .ti3 data sets. Eg: $ verify CHART.sampleA.ti3 CHART.sampleB.ti3 Verify results: Total errors: peak = 79.868037, avg = 0.971652 Worst 10% errors: peak = 79.868037, avg = 5.476613 Best 90% errors: peak = 1.193214, avg = 0.471101 The severity of a few of the errors would suggest possible misreads. They're strip charts I'm reading with an i1Pro by hand (sigh) so operator error (mine) isn't unlikely. It could also be quirks of the printing process and/or newsprint media, since the charts are on off-white partly recycled newsprint printed on a press that does adaptive stochastic dithering. Here's an example error spike: 5: 83.070051 1.346918 2.895409 <=> 82.505987 1.360226 2.779120 de 0.576080 6: 82.110832 1.536077 2.992189 <=> 81.607727 1.437567 2.733480 de 0.574238 7: 40.886825 4.316704 18.048722 <=> 82.063784 1.539669 2.906388 de 43.960711 **** Huge error spike **** 8: 82.523678 1.538664 3.054387 <=> 81.639391 1.422285 2.777460 de 0.933914 9: 82.579391 1.491124 3.066842 <=> 82.226908 1.541316 3.019219 de 0.359209 10: 82.347015 1.442016 3.176074 <=> 80.000400 1.401537 2.851284 de 2.369330 Another: 182: 78.976711 -2.232244 58.087355 <=> 77.775705 -2.120755 56.639930 de 1.884114 183: 80.095716 -2.763189 55.135360 <=> 79.346721 -2.745549 54.804620 de 0.818959 184: 37.428620 -5.000581 0.024627 <=> 78.810882 -2.002915 60.115930 de 73.023573 185: 79.154031 -1.844991 61.359333 <=> 78.829979 -2.012077 60.145829 de 1.267091 186: 78.984785 -1.665758 61.827127 <=> 78.670603 -1.793216 61.269881 de 0.652287 .. etc I know I can average .ti3 sample sets using bin/average. However, it only seems to accept a pair of .ti3 inputs at a time, and averaging consecutively isn't going to produce an ideal result. Is there some good way to average more than two sample sets that I'm missing, or should I just be doing: average a b x average x c x2; mv x2 x average x d x2; mv x2 x average x e x2; mv x2 x ... etc, ie averaging each new set into the accumulated sample set? Also, is there any good built-in way to eliminate outliers in the .ti3 files, or will I need to roll my own ? For that matter, is it wise to do outlier elimination at all? I'd rather not just replace possible outliers in the .ti3 files with samples taken from another .ti3, as that'd bias the average toward one particular sample reading. Any suggestions? If there's no existing method I'm missing, and if what I want to do actually seems like a good idea to the folks here, I'm thinking of seeing if I can extend `average.c' to handle more than two input files. I'd try to add basic outlier elimination for when it has three or more inputs, with the outlier elimination threshold shrinking as the number of input files grows. At this point I'm thinking that any sample more than three (maybe even two) standard deviations from the mean is probably a reasonable candidate for outlier elimination. Also: I've run into an odd issue when averaging the data sets. The output produced by `average' has more sets than the inputs do - both inputs have 2130, but the output has 2364. I'm a bit puzzled about why, given that both inputs were read using `chartread' from charts printed using the same .ps file and had the same .ti1 and .ti2 . Is that expected behavour? -- Craig Ringer

**Follow-Ups**:**[argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets?***From:*Klaus Karcher

**[argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets?***From:*Alastair M. Robinson

**[argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets?***From:*Graeme Gill

- » [argyllcms] bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Craig Ringer
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Klaus Karcher
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Alastair M. Robinson
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Klaus Karcher
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Alastair M. Robinson
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Klaus Karcher
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Craig Ringer
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Craig Ringer
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Alastair M. Robinson
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Craig Ringer
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Graeme Gill
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Graeme Gill
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - edmund ronald
- » [argyllcms] Re: bin/average: averaging and possible outlier elimination for three or more .ti3 sets? - Graeme Gill