Modding, and questions of Windows Camera ISO

[Simon Hinton]

[Got myself a Lumia 735 a few months ago and loved it - coming from WP7, the jump to WP8.1 was fantastic. Except the downgraded performance of Xbox Music (from Zune), IE11 (crashed on sites where WP7 IE was rock solid) and the flaky Skype integration. Hoping Windows 10M would fix this, I installed the insider preview and so far, i'm impressed. Upgrading unofficially (and voiding my warranty) got me thinking of ways to push the phone further...

Considering the 735 has the same cpu, RAM, screen and sensor size as the 830, shouldn't it have the same DNG output capabilities? Windows 10 Mobile seems to be a one-build-suits-all deal, so the code must be there, and disabled on a phone-by-phone basis. I went digging. Derausgewanderte helped me out, and we got it partially working with registry editors. All good so far.

I then found keys for manually changing min and max ISO, potentially getting even crisper images. I set the minimum value at "10", and started snapping. And got stuck.

The images shot with 10 compared to follow up images at 100 and 400; are of course significantly different, and look sharp and detailed when compared to each other. But to me, the quality of the 10 ISO shots seem familiar to what i used to achieve with 100ISO shots on WP8. 100 ISO shots now look like what used to be 400 ISO, and the 400 shots feel like they have the sensitivity of ISO 800 (for example).

How is ISO actually calculated on smartphones? Is there any correlation between the numbers and true sensitivity, or is it all just relative to the limits of the devices sensor? By setting the minimum value to 10, have i shifted the scale to the left, making "10" the new "100" and "100" the new "400"? Have I actually done anything to lower the noise?

Scoured the web, and can't really find much info. Can anyone shed some light?

 

[gpobernardo]

Do you have sample photos?

Take a photo both with the normal un-modded settings and with the modded settings with varying ISO values but with the same shutter speed and the same lighting conditions. For example, a photo of a page of a newspaper with varying sizes of text (this can be reproduced without copyright infringement, unlike books), taken at the same distance each time using a tripod (or with very steady hands).

This way we can accurately compare the performance at different ISO values between the modded and un-modded phone settings.

But I did read a bit further from your posted links... it seems that the ISO values are simply being shifted, since (based on the NPU page you posted) bringing down the minISO also brings down the maxISO value allowable in the camera settings (even if the adjuster allows more).

 

[Simon Hinton]

Do you have sample photos?

Take a photo both with the normal un-modded settings and with the modded settings with varying ISO values but with the same shutter speed and the same lighting conditions. For example, a photo of a page of a newspaper with varying sizes of text (this can be reproduced without copyright infringement, unlike books), taken at the same distance each time using a tripod (or with very steady hands).

This way we can accurately compare the performance at different ISO values between the modded and un-modded phone settings.

But I did read a bit further from your posted links... it seems that the ISO values are simply being shifted, since (based on the NPU page you posted) bringing down the minISO also brings down the maxISO value allowable in the camera settings (even if the adjuster allows more).

Yeah - it makes no difference to the quality :|

Modded ISO10, and stock camera ISO100 images look identical (if anything, the ISO10 ones look worse); so the values are just getting shifted.

Full resolution ones here - slightly misaligned because i had to stop and re-edit the registry to restore the stock values. At least WM10 Camera images seem to be on par with WP8 ones

 

[gpobernardo]

Yup, looks like only some shifting is going on. From my previous testing, higher ISO values translate to larger file sizes (longer exposure time also translates to a larger file size).

Did some readings: many references indicate that digital sensors are made to "perform at their best at ISO 100" although for high-end sensors (better than the average in terms of sensitivity) these are made to perform at their best at ISO 50. Hence, the lowest ISO value is simply an arbitrary baseline value for the sensor when it produces the least noise (no signal amplification done), while the rest of the values are extrapolated from it. In effect, modding the ISO values in the registry doesn't change the actual performance of the sensor; it just re-assigns the baseline best performance of the sensor to a new arbitrary ISO value.

 

[cravani]

[Got myself a Lumia 735 a few months ago and loved it - coming from WP7, the jump to WP8.1 was fantastic. Except the downgraded performance of Xbox Music (from Zune), IE11 (crashed on sites where WP7 IE was rock solid) and the flaky Skype integration. Hoping Windows 10M would fix this, I installed the insider preview and so far, i'm impressed. Upgrading unofficially (and voiding my warranty) got me thinking of ways to push the phone further...

Considering the 735 has the same cpu, RAM, screen and sensor size as the 830, shouldn't it have the same DNG output capabilities? Windows 10 Mobile seems to be a one-build-suits-all deal, so the code must be there, and disabled on a phone-by-phone basis. I went digging. Derausgewanderte helped me out, and we got it partially working with registry editors. All good so far.

I then found keys for manually changing min and max ISO, potentially getting even crisper images. I set the minimum value at "10", and started snapping. And got stuck.

The images shot with 10 compared to follow up images at 100 and 400; are of course significantly different, and look sharp and detailed when compared to each other. But to me, the quality of the 10 ISO shots seem familiar to what i used to achieve with 100ISO shots on WP8. 100 ISO shots now look like what used to be 400 ISO, and the 400 shots feel like they have the sensitivity of ISO 800 (for example).

How is ISO actually calculated on smartphones? Is there any correlation between the numbers and true sensitivity, or is it all just relative to the limits of the devices sensor? By setting the minimum value to 10, have i shifted the scale to the left, making "10" the new "100" and "100" the new "400"? Have I actually done anything to lower the noise?

Scoured the web, and can't really find much info. Can anyone shed some light?

How you managed to change camera values? I've searched everywhere but can't find it.

I really want to make some tests.

 

[Simon Hinton]

How you managed to change camera values? I've searched everywhere but can't find it.

I really want to make some tests.

Its really not worth it, I wouldn't bother. DNG never worked in the end and the ISO functions don't really change much, and you risk irreparably destroying your device for very little gain. Doing any of this will probably void your warranty, unless you manage to revert the phone back to the way it was with the Phone Recovery Tool.

1. Install Microsoft Visual Studio (requires Windows 8 or 10). This is a dependency for "Windows Phone Power Tools"
2. Install Power Tools from here
3. Developer mode needs to be turned on in your device (in Settings somewhere)
4. Sideload unofficial apps from here with Power tools. In my case i needed three registry editors to get my phone unlocked. There's a ton of patching done on Microsoft's side that tries to prevent this, so it's a bit difficult to get away with.
5. Learn how to navigate and write to the registry. This is where you can really break things if you accidentally write the wrong keys in the wrong place.
6. Change keys, as shown here

There's probably steps I've missed but it's nothing i'd suggest anyone do. There's really nothing worthwhile to tweak.

 

[cravani]

Thanks for the tips and instructions.
Unfortunately we can't make any miracles... But it would be nice to shoot in raw with other devices too, like 730 or 640xl.

 

[Simon Hinton]

Thanks for the tips and instructions.
Unfortunately we can't make any miracles...�� But it would be nice to shoot in raw with other devices too, like 730 or 640xl.

Its possible with the 640XL (it's where I got the original idea from), but I think there's a image size buffer or something hardware related stopping my 735 DNGs from saving\going through the system. I'm tempted to just sell up and get an 830, but always chasing flagships is a good way to waste money. I'd just find a shortfall in that phone and want to upgrade a third time

 

[EndOfRope]

Hi,
my L1520 only goes up to ISO 64. I suggest you try this, maybe W10m is not able to handel ISO 10 and goes on with the default ISO 100?

 

[Simon Hinton]

Hi,
my L1520 only goes up to ISO 64. I suggest you try this, maybe W10m is not able to handel ISO 10 and goes on with the default ISO 100?

Yes i have (I took multiple series of images initially, and compared the whole range to a set of unmodded pics). It does work, the EXIF info in the images records an ISO of "10" - but as gpobernardo said, it's just shifting the scale to have 10 as the lowest instead of 100. The quality is no different.