#apertus IRC Channel Logs

hey, how's going?

good

ah, okay?

I have c++ code performing demosaiqing with VNG, apply CameraToXYZ, and XYZtosRGB, and dumping as a TIFF

good job!

right now I'm converting the code to a LUT

yes, I think the lines you stumbled upon should be gone now

awesome

I think there is no reason I won't be able to do Camera to sRGB in 9 LUTs

on paper mathematically it looks good

okay, we actually target 12 luts (i.e. 3x3 for the 'matrix' and 3 for gamma)

hmm

iif the goal is to go to sRGB I think it can all be in one step probably

yeah

but that doesn't matter with the LUT, as it will be pre-built obviously

the code doesn't take long to run, most of the time is spent in the VNG

okay, great

I started to look at the noise/artefacts as well

and I think we can compensate for quite a number of them

sebastian will do more test images later today, so we will know more in the new year :)

awesome

at first i was working on a c++ version of the DNG writer, but got side tracked and worked on the demosaiqing/LUT

but the DNG part just reads tags right now is all

ok sounds good

thanks, cya

Bertl: The XYZ to sRGB / 709 primaries is a 3D LUT.

Bertl: General order of events for any color transform is pretty simple and follows the following outline:

2) Conver the RGB values to XYZ of a given color temperature (your color temperatures must always be aligned for your transforms to XYZ or else all hell breaks loose)

4) Apply the TRC for the destination space. (For sRGB it is a two part formula with an if - a curve with a linear toe. Overall average is ~2.2. 709 has a different two part TRC, and rougly averages to ~1.9)

troy_s: we will do a nonlinear matrix multiplication with a 3x3 LUT (not a 3D lut) and post process with 3 gamma LUTs (which are probably unnecessary but simplify adjustments)

good evening

hello

It looks like I have working LUT code :)

I just made some straylight tests

how did you do the test?

then 3 images with strong light shining on the prototype

now its time to start the cheese fondue before I capture more test images :)

so there are some issues we're going to have to figure out with using the LUT

with the current code if I switch to an int or long there is an overall change in tint in the image

and the LUT has to have signed values, since the matrix can have negative values

seems to work with int

I can push the code to github

its part of my C++ port of the DNG writer

but if you run the Makefile it will also make the code for the LUT

I started putting my tools into https://github.com/apertus-open-source-cinema/alpha-software/tree/master/misc_scripts_and_utilities

sure

https://github.com/apertus-open-source-cinema/alpha-software/tree/master/misc_scripts_and_utilities/dng

aaarrggh

So I am struggling like mad to get OpenEXR 2.1 to compile so that I can get OIIO to compile.

Greets G.

Which is -pthread but it is in there.

Driving me nuts. I would love to even use system OEXR but OIIO insists on looking for an Ilm file in IlmBase that is only in 2.1 and giving fits.

what OS are you using?

gcolburn: I can't stress it enough.

Just update the LUT configs (via GitHub or whatnot)

OIIO has never been an issue for me.

No.

OIIO isn't even needed.

Irking me.

what do you need to determine the gamut of the sensor?

I believe Herbert finished his new firmware update, and sebastian is taking new images

just the ICC profile from argyll?

ok

gcolburn: I can only see pain with the DNG path.

what type of viewer are you referring to?

Well that is 20% errors and colorsync

yeah

catch you guys later

happy new year!

got any fireworks picture? :)