#apertus IRC Channel Logs

the alpha prototype was designed to allow full HD @ 25 FPS and maybe take 4k stills

we already have the 4k stills working perfectly as well as the HDMI output (although not of live images)

i.e. the Zynq can easily handle 75FPS at 4k in the current setup (capture)

and if done correctly, the 150FPS shouldn't be a problem either

the problem is more the output, as the 7020 doesn't feature any multi gigabit tranceivers

Still capable of webpack development

Once I feel competent to contribute some code - what area would is be most helpful for me to focus on ?

right

Morning all.

morning Rambutan2000!

I've been thinking about the design of the case and what features would be good bad. Since this project is open source do you guys think being able to 3d print and/or CNC parts of the case is important?

well, it might not be a primary goal atm, but I guess it would be nice to be able to fabricate certain parts yourself

http://www.youtube.com/watch?v=isQ7cvuyoTw&feature=c4-overview-vl&list=PL1AFF5D9EB822C193

e.g. to implement a serial console in USB 1.1 (not even 2.0) you need a lot of hardware and software, but you can achieve the same with almost no resources using rs232

with higher data rates and newer versions the number of features increases, the hardware gets more expensive and protocols get more complicated

nope

first step will be SDI with external recorder, i.e. no storage at all

off to bed now ... have a good one everyone!

morning everyone!

How goes?

Quiet and sleepy :-)

well, actually we did some calibration tests yesterday and I have written a script to create a perfect IT8 chart based on the sensor data

http://vserver.13thfloor.at/Stuff/AXIOM/it8-tungsten-01-12ms-perfect.png

impressive, how have you made it?

:-)

hello!

I have agryll runing, but I'm not 100% sure I know what I'm doing :-)

problem is that I used some random reference file and don't know if all the command line arguments are right

don't you think it's the error of what the tool can achieve given those colors?

what color space is the image ? :) (one should put that in filename for clarity)

to me, the grays are not gray but yellow...

note that this is not an idealistic chart, it is a perfect version of the actual sensor taking a picture of the chart

I think the error % is based on what the tool managed to produce with the color it received

at least when I apply it to the png file in photoshop, I get an image that looks much more like a good chart

yup, doesn't look completely wrong

IMHO the chart was a little overexposed which shows in the bright areas

philippej: try this chart reference file: www.colorreference.de/targets/R100604.zip

doing right now

S3bastian: btw, the chart image shows quite a number of speckles probably caused by dirt on the sensor

good to know, I will clean the sensor and try to keep the new chart as clean as possible when it arrives

*for

11H, 12F, 4F, 2L, 13H and so on and so forth

weird result, probably caused by weird manipulations :-) http://public.philippejadin.be/it8-tungsten-01-12ms-perfect-with-profile-applied-bis-ok.jpg

do you think the grey "haze" from FPN could be an issue for the calibrations or will it not alter saturation levels?

i.e. it would be really beneficial to take a picture of the chart which fulfills the following requirements:

- even lighting (two light sources, one on each side)

the actual angle doesn't matter much for this approach

Hi gcolburn

hello

14.5% error unfortunately

I would like to understand what this error means exactly

I'll get you the best description I have found of it

I had one chart give me 12.5% yesterday

the images were visually indistinguishable. and those were comparing new chart captures with older ones

"If the -v flag is used (verbose), then at the end of creating a profile, the maximum and average fit error of the input points to the resulting profile will be reported. This is a good guide as to whether things have gone smoothly in creating a profile. Depending on the type of device, and the consistency of the readings, average errors of 5 or less, and maximum errors of 15 or less would normally be expected. If errors are grossly higher than this, th

from the documentation

I got this : Profile check complete, peak err = 17.696363, avg err = 3.949152, is it so bad you think ?

from the CMV12000?

hrbert posted it an hour ago

me too

scanin -v it8-tungsten-01-12ms-perfect.tif It8.cht R100604.txt

yeah. we should have the same one downloaded from the website

that command isn't any different than mine, except I've sometimes turned on perspective compensation

I removed -a(something) to use the default

let me see the difference in our commands

I followed the tutorial, and am quite newbie in this, so take with a grain of salt :-)

for profiling

documentation here : http://www.argyllcms.com/doc/Scenarios.html#PS4

icm file here : http://public.philippejadin.be/it8-tungsten-01-12ms-perfect%20qm%20r.icm can be installed and applied in photoshop for example to test

instead of a LUT for example

Profile check complete, peak err = 44.376942, avg err = 14.835942

but without am it's visually better

as they say about am

but

an of the shelf camera in raw mode is probably, but since we are a step before...

but might be worth reviewing again

yeah

I guess

DNG has tags to embed a matrix for the raw converter to use

sure

interesting

the tool is here : http://www.color.org/profileinspector.xalter (windows only)

see you

see you !

wb gcolburn!

thanks :)

excellent

and I took two tungsten softbox lights home from the university and took a day off tomorrow

those are tungsten or halogen?

seems to be halogen

okay, the spectrum is good on halogen AFAICT, but it has a different color

http://vserver.13thfloor.at/Stuff/AXIOM/scene_daylight_211ms_c2-perfect.png

thank, I will try this one in Lprof now

11.09

8.35

57.23

0.80

the brighter chart had an average dE (I guess this is the error) of around 6

and average dE means?

I think it is essential to put not just a name to those values but also a unit and an explanation what is actually measured

for example, the std deviation, 8.35, what deviates from what here?

dE is short for delta E which is a standard way to measure color errors.

what does peak 57.23 mean? what does peak here, where and why?

shows how close the the color will be once the profile is applies

lprof profile inspection tab is very interesting

what the color should be, what it was

so the error is in comparison to a perfect chart then?

could be, not entirely sure yet

if so, we will never get a lower dE, on the contrary, it will always be wrong

i.e. their 'raw' image will already be post processed regarding color calibration, at least to some degree

so it does take the created profile into account

and where is it off by a factor of 10?

btw, I'm sure there is a list of color values used for the original chart

sure, but what would we do with that list?

create a perfect chart and check what the various tools produce?

wb gcolburn!

http://vserver.13thfloor.at/Stuff/AXIOM/scene_daylight_211ms_c2-perfect.png

not sure if you saw this conversation earlier, but when philippej ran Argyll using a LUT instead of a matrix he had errors less that 4%

I've sort of wondered myself when you run into limitations of a 3x3 matrix… but most literature I read indicates a matrix is best for a camera profile

or to be precise, we are somewhere in between a 3D lut and a matrix

I got 14% error with that one

"If the -v flag is used (verbose), then at the end of creating a profile, the maximum and average fit error of the input points to the resulting profile will be reported. This is a good guide as to whether things have gone smoothly in creating a profile. Depending on the type of device, and the consistency of the readings, average errors of 5 or less, and maximum errors of 15 or less would normally be expected. If errors are grossly higher than this, th

that's all the documentation states

yeah, basically what I figured it did

or the average?

what's the maximum?

well, that is excessive

but as I've said I haven't seen a visual difference between 12% and 20%

phillippej said that when he used the icc profile that was LUT based it looked better to him

if we wanted to switch to the LUT, we'd have to learn about the many LUTs that get embedded in the ICC profile and how to extract/use them

they are icc profiles

oh

or does it try to fit to an ideal chart?

1) Your image

e.g. the reference chart

3) the measurements of the individual chart that we have (R100604.txt)

good

not so good :)

first you run "scan in". it recognizes the patches in your image and determines the values in your image. this outputs a .ti3 file (human readable with the results), then you run "colprof" which will try to fit the data with a matrix or LUT and create an ICC profile

comes with argyll

so you can see which patches it had more variance in

it says 290 boxes, 288 I can explain (12*22 + 24) what are the two missing ones?

hmm, maybe boxes does not necessary mean color areas

ok

here's a semi-theoretical question. how good is 9 degrees of freedom for characterizing the response of an RGB sensor?

DNG uses a matrix

LAB is designed to be more perceptually uniform than XYZ. but it is a transform to go between the two

DNG requiries XYZ

in the LUT code I uploaded I go from camera to sRGB in one step, by combining the camera to XYZ and XYZ to sRGB transforms in one matrix (plus gamma encoding at the end)

can we remove the R100604.txt easily from the equation?

well IT8 charts can be made for different purposes. I believe the R100604.txt is needed for Argyll to understand what to expect from the chart based on the photometric readings that Faust did on the chart

I think the issue is that you can't manufacture a perfect chart

of course, I'm just asking because I would like to do some tests

well there's nothing stopping us from trying our own calibration techniques

we should read up on two things. 1) how the R100604.txt was created

http://www.argyllcms.com/doc/scanin.html

I think the XYZ values of the chart patches have to be measured for each chart as the material, ink, etc. may defer depending on manufacturer and intent of the chart (scanner, camera, printer, etc.)

have you seen this? http://www.argyllcms.com/doc/Scenarios.html#PS1

on my way to bed

will take new captures of the it8 tomorrow

i.e. the first monochrome block at the bottom

well, try to make as many snaps as possible

but with what variations? :)

always do several shots without changing the position

good night!

yeah

because the onlineconverter I found gives me #FBE8CC

by the way, I read this:

so the chart shouldn't be white when it would be perfect or how to interpret this?

the assumed 'black' also gives

hmm

I finally got my colorimeter to work a month ago on my computer and got my NEC LCD profiled. the channels were definitely off :)

I've noticed when I view the DNG there is a brownish ting to the grayscale patches

here's what the Argyll docs say about the .chrt file

anyway, just trying to figure out what the it8.cht values actually mean

well according to that documentation, they don't have to be accurate

which I presume is the measured from the manufacturer (trying to verify that)

I'm pretty sure its the R100604.txt file

so the it8.cht is not used at all for the calibration? except for where to place what color box?

yes, what you said is my understanding

so for coming up with your own calibration

so GS0 is 76.53 79.65 68.26

unless I'm completely wrong, white should map to ~95/100/109 in XYZ

where do you get that from?

with what input value?

guesst: the issue/question is, why would the IT8 chart purposely use non-gray values for gray fields?

my guess is you can't manufacture a perfect gray

I would say, the white photo paper is pretty white, no?

but okay, let's assume the printed IT8 chart has orange-beige in the white field

there must be some definition what color it actually should be

yeah

its in the IT8 standard

so we can read it

i.e. they put some color there which they know is different from what it should be, do I get that right?

I have no idea how they designed the chart. but obviously the goal is to cover a wide gamut of colors

i.e. visualize the chart, but why would you put 'wrong' colors there?

color science is very complicated. some day when I have the time I'd like to read a good book on it

yeah. I think its that way in many fields though

which change over time

I'd like to try running shots from various cameras through Argyll and see what we observe

yeah

anyway, off to bed now ... have a good one everyone!