[libcamera-devel] [RFC PATCH v1] libcamera: isp: Add ISP class

[Fan Siyuan]

Hi paul,


Thu, Sep 2, 2021 at 02:26 PM  paul.elder <paul.elder at ideasonboard.com> wrote:

>Hi Siyuan,

>Thank you for the patch.

>On Wed, Sep 01, 2021 at 02:59:08PM +0100, Siyuan Fan wrote:
>> From: Fan Siyuan <siyuan.fan at foxmail.com>
>> 
>> The ISP class is a abstract base class of software ISP. It includes image
>> format configuration, ISP algorithm parameters parser, pixel processing
>> image export and thread configuration.
>> 
>> This new class will be used as the basic class for ISPCPU and ISPGPU.
>> 
>> Signed-off-by: Fan Siyuan <siyuan.fan at foxmail.com>
>> ---
>> 
>> ISP Parameters Tuning is a important part, so I've designed a parameters
>> parser in order that users can call any algorithm combination by passing
>> any number of tuple. Each tuple format is including algorithm name string
>> and algorithm param, such as tuple<string, int> for black level correct. 
>> Currently this function is only a demo. I'm thus sending it as an RFC.

>I don't quite see how you imagine parse() to be used. Do you "configure"
>the function that you want to run the ISP with first, and then tell it
>to process it? What's wrong with passing the list of command-parameter
>pairs into the processing function directly?
For parse(), we just call it before processing(). In processing(), we won'tpass the param list. If we pass the list of parameter directly, the processing
function should be template function. Maybe this makes  function look
more complicated.

>I think that the processing function should also return statistics. For
>a CPU ISP it's not unreasonable for the control and processing to be
>together, but remember that this interface must be usable for a GPU ISP
>as well, which would have separate control and processing.
sorry, I don't understand why processing() should return statistics. In my view,
the current ISP design needs to separate statistics calibrated/computed
and pixel processing. In processing(), we just process pixel using
param/statistics. Maybe there is no need to return statistics.

>Paul

>> ---
>>  include/libcamera/internal/isp.h | 67 ++++++++++++++++++++++++++++++++
>>  1 file changed, 67 insertions(+)
>>  create mode 100644 include/libcamera/internal/isp.h
>> 
>> diff --git a/include/libcamera/internal/isp.h b/include/libcamera/internal/isp.h
>> new file mode 100644
>> index 00000000..caab7050
>> --- /dev/null
>> +++ b/include/libcamera/internal/isp.h
>> @@ -0,0 +1,67 @@
>> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
>> +/*
>> + * Copyright (C) 2021, Siyuan Fan <siyuan.fan at foxmail.com>
>> + *
>> + * isp.h - The software ISP abstract base class
>> + */
>> +#ifndef __LIBCAMERA_INTERNAL_ISP_H__
>> +#define __LIBCAMERA_INTERNAL_ISP_H__
>> +
>> +#include <vector>
>> +#include <memory>
>> +#include <tuple>
>> +
>> +#include <libcamera/formats.h>
>> +#include <libcamera/framebuffer.h>
>> +#include <libcamera/geometry.h>
>> +#include <libcamera/pixel_format.h>
>> +
>> +#include "libcamera/base/object.h"
>> +#include "libcamera/base/signal.h"
>> +
>> +namespace libcamera{
>> +
>> +class ISP : public Object
>> +{
>> +public:
>> +        ISP() {}
>> +
>> +        virtual ~ISP() {}
>> +
>> +        template<class F, class...Ts, std::size_t...Is>
>> +        void for_each_in_tuple(const std::tuple<Ts...> & tuple, F func, std::index_sequence<Is...>) {
>> +   
>> +                return (void(func(std::get<Is>(tuple))), ...);
>> +        }
>> +
>> +        template<class F, class...Ts>
>> +        void for_each_in_tuple(const std::tuple<Ts...> & tuple, F func) {
>> +                for_each_in_tuple(tuple, func, std::make_index_sequence<sizeof...(Ts)>());
>> +        }
>> +
>> +        template<typename T, typename... Args>
>> +        void parse(const T &head, const Args &... rest)
>> +        {
>> +                for_each_in_tuple(head, [&](const auto &x) {
>> +                        // parse parameters for diff algorithm
>> +                });
>> +        }
>> +
>> +        virtual int configure(PixelFormat inputFormat, PixelFormat outputFormat, Size inputSize, Size outputSize) = 0;
>> +
>> +        virtual void processing(FrameBuffer *srcBuffer, FrameBuffer *dstBuffer,
>> +                                int width, int height) = 0;
>> +
>> +        virtual int exportBuffers(std::vector<std::unique_ptr<FrameBuffer>> *buffers,
>> +                                  unsigned int count, int width, int height) = 0;
>> +
>> +        virtual void start() = 0;
>> +
>> +        virtual void stop() = 0;
>> +
>> +        Signal<FrameBuffer *, FrameBuffer *> ispCompleted;
>> +};
>> +
>> +} /* namespace libcamera */
> +> +
> +#endif /* __LIBCAMERA_INTERNAL_ISP_H__ */> +#endif /* __LIBCAMERA_INTERNAL_ISP_H__ */
> -- > -- 
> 2.20.1> 2.20.1
> >
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