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the sequence of cropping and colour correction makes a difference

PostPosted: Sat Apr 14, 2012 2:07 pm
by marzipano
I just discovered this by accident and I haven't seen any notes in the documentation about it

I took a 360 pano last year of only about 14 images but in lighting that had dark cloud in one direction and the sun going in and out behind clouds - therefore many shots were differently exposed.

This was on handheld with auto settings (no manual on my Nikon pocket digital).

I processed in the normal way
detection -standard 50 cps
some cp editing
optimization - strong
horizon levelling using the levelling button

I then changed the reference image using colour correction and cropped down to get a rectangular image

I noticed that if I cropped first then did the cc I got a completely different (and much much worse!) result than if I did the colour correction first then cropped. I used multiband level 0 for blending and produced jpg files from jpg images in

The 4 below are the two edit results with cc & cropping both ways round and also the two final panos with cc and cropping both ways round

You can see the effect of the different exposures in all but much worse where cropping is done first

Martin

edit - I should have said I was using AutoPano Pro 2.6.2 final

PostPosted: Sat Apr 14, 2012 4:32 pm
by klausesser
looks a bit familiar . . . ;) :

http://www.kolor.com/forum/p97937-today-17-04-59#p97937

best, Klaus

PostPosted: Sun Apr 15, 2012 10:38 am
by marzipano
Same problem but easier to see in these two

Chose reference point 12 for these and rendered both at 100%

1st has no cropping at all performed and reference image manually amended to image 12- came out OK

2nd was cropped to default fit BEFORE using colour correction to amend reference image from APP selection to manual selection of point 12 - blending is terrible

I just have to remember for sets of images with variable lighting conditions to do the Colour Corrections first !

Martin

PostPosted: Sun Apr 15, 2012 10:44 am
by marzipano
oops - needed smaller images

PostPosted: Sun Apr 15, 2012 11:48 am
by CheeseAndJamSandwich
marzipano wrote:This was on handheld with auto settings (no manual on my Nikon pocket digital).
...

A little trick: keep the shutter button half pressed between shots, this should lock all the exposure/wb/etc for all the shots until you've finished. :-)
Try it.

PostPosted: Sun Apr 15, 2012 2:03 pm
by klausesser
marzipano wrote:oops - needed smaller images

oops - maybe i´m wrong, but ColorCorrection should be able to handle this in a better way i guess. Seems CC doesn´t like overexposuring at all.

best, Klaus

PostPosted: Mon Apr 16, 2012 7:59 am
by AlexandreJ
To CheeseAndJamSandwich :
I confirm this : cropping will influence color correction. Technically, it is a bit more complicated and here's the explanation. How does color correction works ?
- According to the current images location, autopano calculates color constraints by analysing all image overlaps.
- Once we have color constraints, we can calculate exposure, color shift for all individual images.

This is why any operation that changes overlapping zones will influence color correction ( individual image move, optimization, crop, etc ).

PostPosted: Mon Apr 16, 2012 10:32 am
by lumelix
Hi Alexandre
> "... by analysing all image overlaps."

Have the size of every image overlap a influence on the resulting CC ?
What if the overlaps are not all the same size, can this result in errors ?

Eg. when shooting a giga pano with a manual pano head, the overlaping zones are irregularly.
Can this be the reason of these errors in the CC I get with some of my panos ?

PostPosted: Mon Apr 16, 2012 4:14 pm
by AlexandreJ
lumelix wrote:Have the size of every image overlap a influence on the resulting CC ?

We have exactly the same concept as CP links with color correction. The influence of a color link is proportional to the area of the overlap zone.
So yes, the more overlap you have, the stronger this link is compared to other links with less overlap.

lumelix wrote:What if the overlaps are not all the same size, can this result in errors ?

No. Errors in color correction can happens because of big moving objects : this will create a wrong link.

lumelix wrote:Eg. when shooting a giga pano with a manual pano head, the overlaping zones are irregularly.

Can this be the reason of these errors in the CC I get with some of my panos ?

No. Big panorama and color correction is still complicated and it could happen that the optimizer doesn't work in this case. We are rewriting this part for v3 ( it's a long job ... ).
In the meantime, the tips we used for Paris26 image does work well ( several yellow anchor everywhere ).

PostPosted: Mon Apr 16, 2012 6:42 pm
by lumelix
Hi Alexandre
Ok, thanks for answer. I will then test it with V3.