Tag Archives: neutral

Opening Raspberry Pi High Quality Camera Raw Files

The Raspberry Pi Foundation recently released an interchangeable lens camera module based on the Sony  IMX477, a 1/2.3″ back side illuminated sensor with 3040×4056 pixels of 1.55um pitch.  In this somewhat technical article we will unpack the 12-bit raw still data that it produces and render it in a convenient color space.

still life raw capture data file raspberry pi high quality hq cam f/8 1/2s base analog gain iso adobe rgb
Figure 1. 12-bit raw capture by Raspberry Pi High Quality Camera with 16 mm kit lens at f/8, 1/2 s, base ISO. The image was loaded into Matlab and rendered Half Height Nearest Neighbor in the Adobe RGB color space with a touch of local contrast and sharpening.  Click on it to see it in its own tab and view it at 100% magnification. If your browser is not color managed you may not see colors properly.

Continue reading Opening Raspberry Pi High Quality Camera Raw Files

How Is a Raw Image Rendered?

What are the basic low level steps involved in raw file conversion?  In this article I will discuss what happens under the hood of digital camera raw converters in order to turn raw file data into a viewable image, a process sometimes referred to as ‘rendering’.  We will use the following raw capture by a Nikon D610 to show how image information is transformed at every step along the way:

Nikon D610 with AF-S 24-120mm f/4 lens at 24mm f/8 ISO100, minimally rendered from raw as outlined in the article.
Figure 1. Nikon D610 with AF-S 24-120mm f/4 lens at 24mm f/8 ISO100, minimally rendered from raw by Octave/Matlab following the steps outlined in the article.

Rendering = Raw Conversion + Editing

Continue reading How Is a Raw Image Rendered?

COMBINING BAYER CFA MTF Curves – II

In this and the previous article I present my thoughts on how MTF50 results obtained from  raw data of the four Bayer CFA channels – off  a uniformly illuminated neutral target captured with a typical digital camera through the slanted edge method – can be combined to provide a meaningful composite MTF50 for the imaging system as a whole1.  Corrections, suggestions and challenges are welcome. Continue reading COMBINING BAYER CFA MTF Curves – II

Combining Bayer CFA Modulation Transfer Functions – I

In this and the following article I will discuss my thoughts on how MTF50 results obtained from  raw data of the four Bayer CFA color channels off  a neutral target captured with a typical camera through the slanted edge method can be combined to provide a meaningful composite MTF50 for the imaging system as a whole.   The perimeter of the discussion are neutral slanted edge measurements of Bayer CFA raw data for linear spatial resolution  (‘sharpness’) photographic hardware evaluations.  Corrections, suggestions and challenges are welcome. Continue reading Combining Bayer CFA Modulation Transfer Functions – I