LibRaw technical support

Stable LibRaw versions: technical support, errors, API questions

Capturing libraw output as if PGM/PPM data

Submitted by David Partridge on

Some code I am working on uses file i/o redirection and calls the old dcraw under the covers.

Depending on the processing options passed to dcraw, the ouput is passed to the code by the following:

// Intercept the fprintf calls in write_ppm_tiff() for PGM/PPM file output.
int Printf(const char *format, va_list va) // intercepts the fprintf calls in write_ppm_tiff()
{
int nResult;
CString strText;

strText.FormatV(format, va);
nResult = strText.GetLength();

AddToBuffer(strText.GetBuffer(10000), nResult);

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Unusual code to check for greyscale image?

Submitted by David Partridge on

I'm looking at some old code that uses dcraw under the covers using file i/o redirection.

The line in question looks like:

m_bColorRAW = is_foveon || !filters;

which is about as clear as mud to me!!!

later on the code then uses this boolean set (or not set) document mode and also sets option -4:

if (!m_bColorRAW)
{
// Document mode (i.e. don't demosaic the image in libraw).
// so set dcraw option "-d "
:
};

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Which aces colorspace is defined in -o 6

Submitted by jt042 on

Hello,

a professor introduced me to libraw because I need to convert my raw files to linear tiff in a defined colorspace.
In the dcraw manpage you can find the argument -o 6 for ACES.
But what aces colorspace is ment by this?
AP1 seems to be a bit to greenish and ap0 a bit to red, but this is only in comparison to my memory.
I attached contact sheet that compares the two here https://ufile.io/chi40f32

Also, is there a way to extract the exact color matrix that is embedded in the .cr2 raw files?

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Edit EXIF data using external library

Submitted by aprofiti on

I would like to know if it's possible to use libraw to edit exif related metadata, by passing data structure to some other library like libexif or similar.

I'm interested in changing Lens related information (name, id, type...), aperture and focal length inside a CR2 file.
.
I had a look to the documentation and found that libraw parse metadata and save the above info in libraw_lensinfo_t and libraw_makernotes_lens_t; if I understand right they are read-only but is possible to install hook for EXIF data when parsing file.

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LibRaw (dcraw?) orientation tag wrong?

Submitted by Mabula on

Hi team,

I am starting to use LibRaw for my own software package (Astro Pixel Processor). I have already written full metadata extraction of TIFF IFDs, EXIF & Makernote tags and Raw conversion of both Canon CR2 and Nikon NEF files.

I have now started with building LibRaw support into my software using Java JNI and I am testing this now on Sony ARW files.

I am able to retreive the Sony arw raw data and I am also able to get certain important metadata values like exposure time, time of exposure, iso etc...

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CMYK Raw Image Data

Submitted by pablobhz on

Hello.
I've tried FastRawViewer and an python libraw(rawpy) parser for reading some CMYK raw image data.
However, none of them was able to read my file.

Until now the only way i've found to read this file is by using Photoshop (opening it there renamed as .raw).
I uploaded a sample of the file i mentioned to google drive:
It is a GrayScale 1-Channel file. Dimensions 305wx374h.

https://drive.google.com/file/d/1NHgeJtGw3tZS7IJFJYpJYg-Tkb9lMlc1/view?u...

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