#apertus IRC Channel Logs

troy_s: http://vserver.13thfloor.at/Stuff/AXIOM/RAW/self_10ms.png is this more what you 'expect' from a real world scene?

hoho, the prototype is getting self-aware :)

good night

there is a 15ms and 20ms version as well, and of course, the 16bit raws for all of them

Bertl:

I've got to head out. If you get a chance could you send me an email with more details on the bit order and the first couple pixel values for the image "colors_400ms.raw16"? I can successfully read a DNG, and re-write the image to a DNG (excluding thumbnails) and open it in photoshop raw. My first test will be to just replace the image from a Canon camera with one from the CMV12000, and then after that I'll work on writing a DNG with minimal tags.

Evening !

evening FergusL

Correct

http://vserver.13thfloor.at/Stuff/AXIOM/RAW/linear_2.svg regarding this

but in that case, I was expecting to be indeed straight

Bertl: about the real world scene ? it could be identified as linear if the scene was visually well exposed

FergusL: I'd say it was well exposed with the floodlight directly beneath the board :)

and actually it is big endian, but the values are padded to 16bit on the lsb side

you didn't change anything from the color tapes pictures ? exepct for the exp tie

it has f/11 but the sensor settings should be the same

hm... I see

hehe, well, I guess you are still fighting with yourself over the linearity measurements, right?

I think I simply didn't understand "what" exactly the curves say

I understood the test I think : plotting data from the sensor of the evolution of brightness received

yep, physics says that a point light will have even illumination in all directions

and because the light will radiate in all directions, it will get dimmer relative to the surface of the sphere with a radius equal to the distance

so you expect a 1/(r*r) behaviour there

now something similar happens when you shine light on a diffuse surface (like paper)

this gives you a cos(theta) behaviour

yes

still with you

i.e. D^2 + x^2 = d^2

on the other end (the cosine law) we get

both combined basically give cos(atan2(x,D) * C/(D^2 * x^2)

still with me?

the other end being the diffuse reflection

so that formular gives us a few nice curves

http://vserver.13thfloor.at/Stuff/AXIOM/RAW/linear_2.svg (the dark colored ones)

make C = 1.1, we get the dark red curve

(ignore the fuzzy curves for now)

why these values ? am I asking because I missed something

i.e. they give a field of curves for all different Cs

ok

ha, yes

(well, I'm lying, but hey :)

http://vserver.13thfloor.at/Stuff/AXIOM/RAW/linear_test2_c0_32.png

http://vserver.13thfloor.at/Stuff/AXIOM/RAW/linear_test2_c1_32.png

i.e. we sort the values in each column from lowest to highest

to remove most dead/hot pixels

and the 16 values we have left, we simply add together

yes

hm, yes

and we find that there are close matches at C=1.1 for red, C=0.8 for green and C=0.4 for blue

and we 'see' that the curves are quite similar to eachother

of course, on the far right side, the lamp itself destorts the measurement

i.e. we do not see the reflected light on the paper, we see the lamp instead

but what we now can do is calculate f(x)/g(x) for f(x) being the measured values of (x) and g(x) being the calculated values for x

I actually dropped the 'C' from g(x) so I'm using h(x) which is the original calculated funtion without the C

what does "sqd" mean ?

I see

and basically if you draw a horizontal line for each color component, that would mean a perfect fit

yes

linear_2

i.e. linear_2 could still look similar but the curves in linear_1 would bend or have an angle

yes, it is the relation of those C factors

it is caused by the sensor defect on the left side of the picture :)

so everything clear now?

good! :)

.xz

i.e. lossless compression

what are the raw16 files like ? direct binary dump ?

are developpers supposed to use this as-is and write code to handle ,files that way ?

yes

we added the register dump yesterday/today

maybe I can try to do something with OCIO and python

so the new files are slightly larger (256 bytes) but contain the register values

yup

no, the human is not part of the equation :)

can't remember which one...

the C factors depend solely on the light source and the spectral response of the sensor

as we have no idea about the spectral response of the sensor, we just don't know

I just ignored one green channel completely

cause the ratio of Red and Blue are about right for ntsc

The Green would actually be a bit undercompensated, but still in a somewhat similar proportion

I'd say the light source was mainly in the red spectrum, with more reds than greens and only little blue

hmm

or what would look white to you?

I'd be curious to see the response to a white bulb

night guys

cya, have a good night!

thanks for all your efforts :)

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

hello se6astian

great

ping Bertl ? from what I can understand, the bayer pattern should be RGGB

the bayer2rgb calls it RGGB

and G B G B in the second row

so 4 pixels (2 from each row) give the RGGB pattern when read from left to right and from top to bottom

twitter, fb and g+ propaganda released

writing to news websites again now

do you use invert Y Bertl ?

I used both, depending on the test case and motive

it is recommended, because otherwise the image will be mirrored :)

actually I had forgotten that

actually it is more the way how CMOSIS numbers the rows, but yes, mirrors are fun :)

compiled with py bindings, all fine

oh, oiio even has interpolation functions

The apertus° association will hold its 2013 general assembly in 2 weeks

all members are invited

the only requirement is to have made a contribution to the project

shall I apply for a membership?

I think you fullfil the criterias by a tiny margin :P

FergusL: what do you want to use python *for*?

I wouldn't use python for low level data manipulation (though it would be reasonable to use it if the number of images you need to dump is small)

but I agree, indeed

or maybe I should seek on-demand to the desired byte...

http://www.slashcam.de/news/single/Erste-4K-RAW-Bilder-vom-Apertus-Axiom-Prototypen---10995.html

interested ? interested in helping ?

Briefly here

troy_s: you used oiio, right ?

(Which is ideally a Cineon or JoshPines Log probably, as those are very much reference standard logs for grading)

I have used OIIO, but via C.

(to dump raw YCbCr from a video stream into a TIFF)

It is pretty simple.

(page me if you direct to me now. I am on notify mode for a few)

I'm going to try on a small debayer program

dinner, later !

FergusL: Do VNG interpolation