Zebras

@reyalp

When manually ETTRing the CHDK histogram warning and the Zebras combine to provide a very powerful tool.

The one weakness I personally find is that the current Zebra functionality is only enabled/seen when you carry out a half shutter press.

When adjusting exposure, ie ETTRing, you don't really want to keep holding the HS down.

Is there any chance you would consider adding a third option. Namely always on or flash on every x seconds?

Cheers

Garry

... Zebra functionality is only enabled/seen when you carry out a half shutter press.

Maybe the reference value is only available/valid in half press? 

Maybe2: An option to draw while AE locked? 

@Caefix

The CHDK manual clearly says the zebras only work when a HS is pressed.

I don’t know if it is coded this way because the original author of the code decided that was the way it was going to work, or that it must work that way and only that way.

Hopefully, @reyalp will have the backstory.

The condition to draw seems ...  // zebra.c ~710
int gui_osd_draw_zebra(int show)
...
    if (timer==1)
    {
        int ready;
        if (!camera_info.state.mode_rec) ready=1;
        else get_property_case(camera_info.props.shooting, &ready, 4);
        if(!ready) return 0;
...

@Caefix

It’s not clear to me how that snippet of code links to half shutter press.

// include/propset9.h
#define PROPCASE_SHOOTING_STATE                  359        // Goes to 1 soon after half press, 2 around when override hook called, 3 after shot start, back to 2 when shoot_full released, back to 0 when half released
#define PROPCASE_SHOOTING                       1001        // fake, emulated by wrapper using SHOOTING_STATE
... Sitting beside You, awaiting background story. 

I don't think there's any backstory beyond whoever wrote it not expecting anyone to want zebra on all the time.

In trunk r6100-6101, I changed the draw zebra option from a checkbox to an enum with options: Never, Shoot, Rec, Always.

"Shoot" is equivalent to the previous zebra ON setting. "Rec" displays it when the camera is in rec mode, and "Always" also enables it in playback.

This is similar to the options for histogram, although the exact behavior may not be the same, and the order is different to keep the first two settings compatible with existing cfgs.

However,  the digic 6/7 drawing code does not actually allow drawing/updating zebra and histogram at the same time, so this probably not useful for most of your cameras. Maybe I'll fix it, or maybe I'll give up and revert the whole thing 

(edit: I haven't bothered merging to the ximr branch because of this)

Notes:
* Zebra does not draw in alt mode, unlike histogram when set to "rec" or "always"
* The existing logic used for the "Shoot" option is only applied to still (not video) shooting modes. "Rec" and "Always" are applied regardless of mode.
* Zebra in playback mode behaves like activating with half press did, meaning that if the image isn't full screen, stuff outside the image will be treated as underexposed.

@reyalp

Thanks for the insight, I understand now why the XIMR builds lack the ‘always on’ functionality for zebras.

Maybe @philmoz can say if it would be possible to get the XIMR builds updated, ie options to allow histogram and zebras to be on all the time, separately and together.

Having said that, users like me are totally in the hands of the developers to implement such functionality in the XIMR builds.

Cheers

Garry

Thanks for the insight, I understand now why the XIMR builds lack the ‘always on’ functionality for zebras.

Maybe philmoz can say if it would be possible to get the XIMR builds updated, ie options to allow histogram and zebras to be on all the time, separately and together.

The problem applies to digic 6/7 generally, it's not specific to the ximr code.