HowTo? Determine whether highlights blown in ETTR RAW file? Need to "zero" all ACR settings?

Started Oct 13, 2012 | Questions thread
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l_d_allan Veteran Member • Posts: 4,946
HowTo? Determine whether highlights blown in ETTR RAW file? Need to "zero" all ACR settings?

Canon 5dm2 and T3i (but I think applicable to most/all cameras that can shoot RAW)

I'm unclear how to tell if pixels are over-exposed in a RAW capture, and are actually the equivalent of RGB(255,255,255 ... ie ... blown highlights).

My understanding is that the histogram (and "blinkies") on the camera LCD are from the JPEG engine, so they differ from "ETTR RAW Reality" when shooting RAW ... there is invariably some "head-room" even when the camera indicates overexposure with "blinkies".

However, the default settings for ACR Process Versions 2003/2010/2012 also manipulate the image. With ACR 7.x (Process Version PV-2012), my understanding is that the "Linear" tone curve isn't actually Linear, but has some contrast enhancement with a default S curve.

Can the actual RAW values be observed with the ACR Sampler by setting all PV-2010 ACR sliders to zero, Linear tone curve, and "Camera Profile" to "Neutral"? This results in a rather flat, drab, low-contrast, and low saturation image in the ACR viewer, but does this more closely correspond to the actual RAW values that the sensor captured?

I'm especially unclear on whether the PV-2010 "Blacks" slider should be zero'ed, and how the 2.2 gamma factor is or isn't involved.

 l_d_allan's gear list:l_d_allan's gear list
Panasonic Lumix DMC-TZ3 Panasonic Lumix DMC-FZ47 Canon PowerShot S110 Canon EOS 5D Mark II Canon EOS 600D +28 more
This question has not been answered yet.
Canon EOS 5D Canon EOS 600D (EOS Rebel T3i / EOS Kiss X5)
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