#apertus IRC Channel Logs

hey, do you gus an gals not have a real-live bug-tracking system? (email doesn't count)

good morning

djp: not yet, currently there are no bugs, only features :)

troy_s: a method to determine the native iso/ei which does not require expensive measurement devices would be handy

that is what we do not have

Bertl: With "canned" aspects. The reality is often you are generating customs - some folks want a center dot, some a crosshair, some different aspects, some offset to upper third (think cropping)

how to chart it?

troy_s: yes, I understand that, the other side of the coin is that overlaying an alpha blended image costs a lot of resources and thus will reduce the lifetime of the battery

Bertl: Gotcha.

for example, simply drawing a few horizontal and vertical lines or darkening a few areas doesn't cost anything

that's why I'm asking :)

it might be an option to integrate it in the HUD and make it regional or optional

that's not a problem

Bertl: Go crawl over the Alexa and F65 docs.

the process of overlaying images doesn't cost much in the FPGA resource wise, the problem is more with fetching an image from memory over and over

Anyways... important and slightly more complex than first glance.

(what isn't)

mars_: does sebastian know this? :)

http://rofitv.files.wordpress.com/2010/02/sekonic.jpg

Bertl: fetching the overlay is costly? (of bandwidth or of power)

danieel: I am sure Bertl can lend some insight into finding the native EI as well. Should be that crossover point of balanced latitude I believe.

danieel: Because if you look at the charts for latitude on the f65 for examplr

I'm cleaning up code and fixing a few tools which got broken during the latest updates (double buffered live view) but when I'm done, I'll look into all the calibration stuff

danieel: But rather EI shifts the exposure range up and down

danieel: But shifts the amount down or up.

btw troy I just shot a new chart series for you

se6astian1: YOU ROCKS

se6astian1: Will do it first thing this morning if you get them up.

troy_s: so instead of getting a spot meter you suggest to get an f65? :)

danieel: No, I am sure Bertl can explain it better. ISO on film was larger crystals of silver where here it is just gain

danieel: And while analogous, the EI / ISO effectively doesn't adjust the latitude other than offset.

danieel: Magic Lantern just did a huge bunch of tests and plotted the EI

danieel: Yes and I believe (again open to error) that the point where the latitude over / under paths cross

So if you have 12 stops of latitude

ok... so we shoot a fade chart

the thing is, with the different gain and offset setting present in each sensor (not just the cmosis) it is rather complicated to 'calculate' an ISO equivalent for the sensor, you can only do it for a certain setting

Bertl: Yes and EI / ISO is kind of damn important LOL

shoot at 360deg shutter?

danieel: Shutter shouldn't matter

will get the old chart tonight, and will see if it makes sense to investigate

danieel: And expose up and down. When those are both hit, the neutral center is native (or darn close)

Bertl: Or calibrated spot with an emissive patch?

which one :) http://www.wikiradiography.com/page/Exposure+Index

on raw linear data

danieel: That floats I believe

yes, the test should be using same lens aperture, ideally on studio light and fixed patch

where F is the f-stop, and t is the exposure time

makes sense.. but the BASE ei has what base time?

i think bertl described ei as the base iso multiplier

Incoming new photos at 108 megs.

Bertl: That's the baseline and why it is rather important.

Would be great if there were a few more hacks that can code in here.

Bertl: If we knew the primaries of the filters, we could get a transformation matrix. :)

se6astian1 / Bertl: are you both on the same firmware? It seems sometimes I get unflipped images?

but we will know shortly

Bertl: It was odd that I was having to flip flop the basic demosaics

the debayer algorithm on the wiki (imagemagick) for flipped images gives the correct colors

Bertl: So I've started in here... the general trend is that the error goes up as the exposure is going up.

(as in irregularity or?)

Bertl: Why is that?

bad filter?

Not a bad theory.

Even in > D50, the red channel is really grabbing on.

if you look at the spectral response, the red channel can handle all the range from 570nm up to 850nm

Bertl: I looked at that chart... it just seems that the red is heavily overweighting the values.

green and blue is significantly less sensitive in the 'lower' IR range

Bertl: Any way to test your theory?

Bertl: The good news is that our DE2k is down to 8.09

Bertl / se6astian1 Here's the 16 ms profcheck results http://www.pasteall.org/49827

(The 16ms (the lowest se6astian1 shot) yielded the best results, which is _entirely_ odd given that the RGB values are being read at 77-78 maximum.)

What's _really_ odd Bertl is that in the GS row (the achromatics) the colors vary wildly.

(And by wildly I mean the white box (00) is off by a notable amount compared to say, the box adjacent it, etc.

Bertl: The data values in terms of achromatic balance shifts dramatically.

So the sensel capturing across the achromatic strips is varying left to right significantly dramatically.

sounds indeed odd

Bertl: The first link.

The DE is very high (in red channel I'd again say) for 00 and 01

So as we increase and decrease away from our 'middle exposure' zone, our deviation appears to be flying off the charts.

That's the blue strip

Bertl: Notice a trend?

Bertl: Look at the profile check

Bertl: That's the blue strip on the IT8

Bertl: Look as we start BRIGHT in the bluey cyans

The DE is off the chart

the only time it gets into a viable range of 2.++ ish

except for GS00-02

The shift is very uniform from middle grey across the board

same thing

So something is going on at all non-middle grey exposure values.

(it is _way_ off)

Whack.

Bertl: So blue is notably out of whack, which show sup on the yellow, blue, and neutral swatches quite dramatically.

(seems to deviate MUCH more in those ranges)

not completely, but you never know, I also suspect irritating results from incorrect offsets

for example, with the cap on, the default offset setting gives a peak around 250/4096

and most importantly, on this peak all four channels converge

probably resulting in quite a strange profile

Bertl: That's the diagnostics chart (for the 24ms version as an aside) so you have chart values to look at.

the color changes on GS00-03 are probably due to the low chromatic component in bright gray swatches

so the twist in the profile kicks in when reconstructing

(Side note to all passive onlookers, please do not consider the "color" in that diagonstic image as being sRGB. It isn't. It is arbitrary and undefined. What you are seeing is nothing more than raw data being dumped to sRGB)

so any error is amplified there and gives a tint in one or the other direction

It shouldn't be that out of whack. Not in a million zillion years.

Bertl: And look at the TI3 data for the GS row (the achromatics)

Bertl: Or rather, look how hyper the red channel is?

but for some reason it seems to be getting hyper excited when we drift from middle grey exposures.

se6astian1: By the way, fantastic exposure bracket for this lot.

Bertl: Here's 28ms (with channels peaking at around 92/93 RGB)

Bertl: and the TI3

(Well high is 94+)

That's decent.

Hell F03 is 1.01!

Anyways, look at the DE readouts (the profcheck) on that more ideal exposed chart.

(A red swatch)

we will get some clues shortly

I have some tests to do to clarify what happens in the IR range

Hrm. Interesting.

But you and se6 are in different regions, so it is unlikely to test with proper charts?

more importantly it is already dark

LOL

The daylight isn't THAT big of an issue.

there are two ADC offsets, one for the top ADCs and one for the bottom ADCs

Per channel?

Hrm. So what would adjusting those offsets do?

Bring the skew / fanning of the three channel curves into alignment?

That makes good sense.

with the filters, I also get the 'old' IT8.7 chart back

precisely

I also have a neutral gray here somewhere

That might help to dial in those ADC offsets?

You can probably use the error as a guide, as I think that is a linear error.

I can do a bunch of tricks with the gamma lut

How does that help here?

I mean viewing output can be a 3D LUT and could likely correct for any mess

So the root issue is more important than cheating something closeish.

?

So use the liveview as a diagnostics device of some sort?

you know what a gauss curve is?

And the good news is I am stupid.

Bell curve? Parabola?

bell shaped curve is the one I mean

Ah gotcha.

So sort of a false-color readout.

False colors are handy as hell.

and of course, I can also apply it to all channels

so there are a number of options to simplify adjusting various things with help of the live view

Well whatever. Get it fixed in the next twenty minutes. kthxbai.

hehe, will do :)

off for a nap ... bbl

hey

Hi! welcome Sébastien

we have logs available on irc.apertus.org as well

time for bed..