New version 1.3.2 of the DSLR_RAW module

Juan Conejero

PixInsight Staff
Sep 2, 2004
8,283
408
57
Valencia, Spain
pixinsight.com
Hi all,

I have just released an update with a new version of the DSLR_RAW module for all platforms: 1.3.2.313. This version adds new options to continue exploiting more features of the DCRAW back end, written by Dave Coffin.

New Features

No image crop

Most (all?) digital cameras don't expose the entire sensor area. This means that what is normally downloaded from a digital camera is not the whole raw frame, but only the picture area, which excludes several 'unused' regions of pixels. This has been also the case of PixInsight, until now. Version 1.3.2 of the DSLR_RAW module provides a new option, namely no image crop, available on the RAW Format Preferences dialog.

When this option is enabled, the whole raw frames are loaded, including unexposed regions. In general, these regions are different for each camera brand and model. For example, the Canon EOS 5DS has two unexposed regions: one at the left side of the frame with 160 columns of pixels, and a second one with 64 rows at the top. The Nikon D3, on the other hand, has just two columns of two pixels each at the left and right sides of the frame. Note that these unexposed areas are not just image borders; they are real sensor pixels with their own signal and noise. In the case of all Canon cameras I've seen, at least, unexposed areas don't show any Bayer pattern, so they seem to be not covered by the CFA filter. I am sure that many users with much more direct experience with camera hardware will know more about this.

In my opinion, unexposed raw frame regions could be useful as overscan areas, at least for some camera models (Canon, mostly). Our preprocessing tool set fully supports multiple overscan regions, so this option directly opens a door for experimentation. At the very least, it provides us with more flexibility, which is one of the leitmotifs of PixInsight.

This option is always disabled by default. It can only be applied when loading raw, uninterpolated frames, so it is ignored when one of the interpolation options is selected.

No white balance

When this option is enabled, interpolated digital camera images will be loaded without any white balance scaling applied. By default, when this option is not selected, and none of the other white balance options is selected either (namely, automatic and camera white balance), DCRAW applies a default set of camera-dependent daylight multipliers. For informative purposes, the values of these multipliers are always written to the console when you load a digital camera image, along with other important metadata items such as frame dimensions, CFA patterns, color spaces, etc.

With this option enabled, the DSLR_RAW module behaves just as the Debayer tool, that is, the raw pixels are loaded and interpolated as they are stored in the device, without any additional white balancing transformation. Note however, that DCRAW always rescales interpolated images, which Debayer does not.

This option is disabled by default. Obviously, its value is always ignored when raw CFA data are loaded (including the superpixel mode and both single-plane monochrome and RGB CFA options).

New Format Hints

This version also implements new format hints to provide access to the new options. For reference, this is the complete list of the input format hints available in the new version of the DSLR_RAW module:

raw
Selects a set of options to load pure raw data as an RGB color image.

preview
Selects a set of options to load a de-Bayered RGB image with half-size interpolation.

bilinear
Selects bilinear interpolation for de-Bayering.

fast
A synonym for "bilinear".

vng
Selects VNG interpolation.

ppg
Selects PPG interpolation.

ahd
Selects AHD interpolation.

half-size
Selects fast half-size interpolation (intended for previewing images).

interpolate-as-4-colors
Enables the interpolate RGB as four colors option.

no-interpolate-as-4-colors
Disables the interpolate RGB as four colors option.

auto-white-balance
Enables the automatic white balance option.

no-auto-white-balance
Disables the automatic white balance option.

camera-white-balance
Enables the camera white balance option.

no-camera-white-balance
Disables the camera white balance option.

no-white-balance
Enables the no white balance option (hence, disables white balancing for interpolated images).

daylight-white-balance
Disables all white balancing options. Enables dcraw's daylight multipliers.

super-pixels
Enables the create super-pixels option. Implicitly disables the create raw Bayer RGB image and create raw Bayer CFA image options.

no-super-pixels
Disables the create super-pixels option.

bayer-drizzle
Enables the create raw Bayer RGB image option. Implicitly disables the create super-pixels and create raw Bayer CFA image options.

no-bayer-drizzle
Disables the create raw Bayer RGB image option.

cfa
Enables the create raw Bayer CFA image option. Implicitly disables the create super-pixels and create raw Bayer RGB image options.

no-cfa
Disables the create raw Bayer CFA image option.

auto-flip
Disables the no image flip option.

no-auto-flip
Enables the no image flip option.

auto-crop
Enables automatic crop of unexposed frame regions (always enabled by default).

no-auto-crop
Disables automatic crop of unexposed frame regions.

black-point-correction
Disables the no black point correction option.

no-black-point-correction
Enables the no black point correction option.

clip-highlights
Disables the no highlights clipping option.

no-clip-highlights
Enables the no highlights clipping option.

noise-threshold <n>
Sets the noise threshold parameter to the specified integer <n>. If <n> is zero, disables the wavelet noise reduction feature.

no-noise-reduction
Disables wavelet noise reduction. Equivalent to "noise-threshold 0".
 

NKV

PTeam Member
Dec 3, 2008
677
0
Juan Conejero said:
Note however, that DCRAW always rescales interpolated images, which Debayer does not.
So, is no way to get equivalent result.
a) RAW > DSLR_RAW > RGB16 >  RGB32
b) RAW > DSLR_RAW > CFA > Debayer > RGB32

a != b
 

Juan Conejero

PixInsight Staff
Sep 2, 2004
8,283
408
57
Valencia, Spain
pixinsight.com
These should be equivalent:

a) RAW > DSLR_RAW > RGB16 >  RGB32
b) RAW > DSLR_RAW > CFA > Debayer > RGB32 > Rescale

Just be careful not to alter chromatic balance when rescaling, that is, rescale each channel to the min/max range computed for the whole image. The RGB/K option of the Rescale tool does just this.

Unfortunately, I don't see an option to disable this final rescaling in dcraw.