libcamera: software_isp: Add Debayer base class

Add a base class for debayer implementations. This is intended to be
suitable for both GPU (or otherwise) accelerated debayer implementations
as well as CPU based debayering.

Doxygen documentation by Dennis Bonke.

Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> # sc8280xp Lenovo x13s
Tested-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Co-developed-by: Dennis Bonke <admin@dennisbonke.com>
Signed-off-by: Dennis Bonke <admin@dennisbonke.com>
Co-developed-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/libcamera/software_isp/TODO b/src/libcamera/software_isp/TODO
index 1c28fc36..7929e73e 100644
--- a/src/libcamera/software_isp/TODO
+++ b/src/libcamera/software_isp/TODO
@@ -69,3 +69,34 @@ Removing the signal and refactoring those classes doesn't have to be
 addressed now, I think it would be part of a larger refactoring
 (possibly also considering platforms that have no ISP but can produce
 stats in hardware, such as the i.MX7), but please keep it on your radar.
+
+---
+
+4. Hide internal representation of gains from callers
+
+> struct DebayerParams {
+> 	static constexpr unsigned int kGain10 = 256;
+
+Forcing the caller to deal with the internal representation of gains
+isn't nice, especially given that it precludes implementing gains of
+different precisions in different backend. Wouldn't it be better to pass
+the values as floating point numbers, and convert them to the internal
+representation in the implementation of process() before using them ?
+
+---
+
+5. Store ISP parameters in per-frame buffers
+
+> /**
+>  * \fn void Debayer::process(FrameBuffer *input, FrameBuffer *output, DebayerParams params)
+>  * \brief Process the bayer data into the requested format.
+>  * \param[in] input The input buffer.
+>  * \param[in] output The output buffer.
+>  * \param[in] params The parameters to be used in debayering.
+>  *
+>  * \note DebayerParams is passed by value deliberately so that a copy is passed
+>  * when this is run in another thread by invokeMethod().
+>  */
+
+Possibly something to address later, by storing ISP parameters in
+per-frame buffers like we do for hardware ISPs.