The larger the data span in a 16-pixel block is, the larger the step is, which is multiplied by the delta value to restore the pixel value, and consequently the larger the data step is.
Thus the raw data compressed per cRAW scheme effectively uses 1 byte per pixel but the total ARW2 file size is slightly larger as it contains not only cRAW data, but also metadata and JPEG preview. Here, Max is the maximum pixel value in the block, Min is the minimum value in the block, Offsets are the positions of pixels with Max and Min values relative to the block startĭelta = (PixelValue – Min) / Step (see more on this below) The artifacts in the form of a horizontal color fringe on both sides of one of the star trails are very visible even if all of the sliders are set to zero, except the exposure slider: Koski who now gave us his permission to link to the original raw file _DSC0035-startrails.ARW Lets have a look at the example provided by Matti Koski, it is the same example that was published by Lloyd Chambers in his blog. All that is necessary for the artifacts to threaten the quality of the final image is a combination of high local contrast and a flat featureless background. With some unlucky stars in alignment, the artifacts can become plainly visible, even without much image processing. In the vast majority of cases, the compression artifacts are imperceptible unless the heavy-handed contrast boost is introduced. We will be discussing the technical details of this compression in the second part of this article.
Sony raw file converter how to#
The first part of this article is showing how to detect artifacts caused by this compression.
Sony raw file converter series#
Lossy compression of raw data is currently the only option available in Sony cameras of series NEX, SLT, RX, ILCE, ILCA, and the recent DSLR-A.
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