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marCCD frames are widened on the device

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The marCCD reader read each frame's 16-bit scanlines into scratch and widened them to int32 on the
worker thread (marccd::ReadInto, ~20 % of the image-loop worker CPU on 4nwv), and the 4-byte image was
uploaded. ReadRawImage now reads the scanlines straight into the image's buffer and hands them over as
a new read-only CompressionAlgorithm::UINT16_WIDENED (mode Int32): two bytes a pixel cross PCIe, from
page-locked memory, and the preprocessing kernel widens them itself.

It is not CompressedImageMode::Uint16, which calls 65535 an error pixel; a marCCD's 65535 is its
saturation marker. So the kernel compares each pixel with int32's error marker and the int32 saturation
cap - the comparisons are made on the pixel's value, in int64, rather than in the storage type - and
decides every pixel exactly as for the int32 image the host would have widened it to. The host widening
(JFJochDecompressPtr) is the CPU path.

Test: ImagePreprocessorGPU_StoredEncodingsMatchCPU, with a frame carrying 65535 at a saturation of
65535, against the CPU preprocessor on the host-widened image.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EizBKhTqrAYago9KJG3dA3
This commit is contained in:
leonarski_f
2026-10-12 22:37:47 +02:00
co-authored by Claude Opus 5.5
parent f4252ad39d
commit dfd69fcb91
10 changed files with 94 additions and 30 deletions
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image_analysis/image_preprocessing/ImagePreprocessorGPU.h
+7 -4
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@@ -38,14 +38,17 @@ class ImagePreprocessorGPU : public ImagePreprocessor {
// Which decoder the last AnalyzeCompressed used, for GetLastDecompressionTime_s.
enum class LastDecode { None, BSLZ4, CBF } last_decode = LastDecode::None;
// The file encoding of the miniCBF reader (CompressionAlgorithmEnum.h): the stored bytes are
// uploaded, decoded into gpu_decompressed_image as the int32 image the host would have produced,
// and preprocessed by the same kernel as an uploaded int32 image.
// The file encodings of the miniCBF and marCCD readers (CompressionAlgorithmEnum.h): the stored
// bytes are uploaded, decoded into gpu_decompressed_image as the int32 image the host would have
// produced, and preprocessed by the same kernel as an uploaded int32 image.
ImageStatistics AnalyzeStoredInt32(ImagePreprocessorBuffer &processed_image, const CompressedImage &image);
template <class T> ImageStatistics Analyze(ImagePreprocessorBuffer &processed_image, const uint8_t *input, T err_value, T sat_value);
// Preprocess an image already sitting in gpu_decompressed_image (the host-upload path).
template <class T> ImageStatistics AnalyzeOnDevice(ImagePreprocessorBuffer &processed_image, T err_value, T sat_value);
// err_value and sat_value are compared with the pixel's value, not its bits, so a narrower T can
// carry the int32 semantics of the image it widens to.
template <class T> ImageStatistics AnalyzeOnDevice(ImagePreprocessorBuffer &processed_image,
int64_t err_value, int64_t sat_value);
// Preprocess straight out of the bitshuffled bytes (the device-decode path). Same per-pixel
// decision and same statistics as AnalyzeOnDevice, with the un-transpose folded in.
template <class T, int ES> ImageStatistics UntransposeAndAnalyze(ImagePreprocessorBuffer &processed_image,