[PATCH 2/3] apps: common: dng_writer: Add thumbnail scanline function for RawXX

[Laurent Pinchart]

Hi Stefan,

Thank you for the patch.

On Thu, Jun 27, 2024 at 02:51:10PM +0200, Stefan Klug wrote:
> Add a thumbnail function for raw formats that are 16bit aligned.
> This is needed for the upcoming RAW10 and RAW12 implemntation.
> 
> Use the new function for RAW16 as the thumbScanlineRawXX_CSI2P produces
> incorrect results for that format (it averages over adjacent bytes,
> which works for the CSI formats).
> 
> Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> ---
>  src/apps/common/dng_writer.cpp | 32 ++++++++++++++++++++++++++++----
>  1 file changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/src/apps/common/dng_writer.cpp b/src/apps/common/dng_writer.cpp
> index 88b225d3e099..2cb320ff327b 100644
> --- a/src/apps/common/dng_writer.cpp
> +++ b/src/apps/common/dng_writer.cpp
> @@ -144,6 +144,30 @@ void packScanlineRaw16(void *output, const void *input, unsigned int width)
>  	std::copy(in, in + width, out);
>  }
>  
> +/* Thumbnail function for raw data aligned to 16bit words */
> +void thumbScanlineRawXX(const FormatInfo &info, void *output,
> +			  const void *input, unsigned int width,
> +			  unsigned int stride)
> +{
> +	const uint16_t *in = static_cast<const uint16_t *>(input);
> +	const uint16_t *in2 = static_cast<const uint16_t *>(input) + stride / 2;
> +	uint8_t *out = static_cast<uint8_t *>(output);
> +
> +	/* shift down to 8 */

	/* Shift down to 8. */

> +	unsigned int shift = info.bitsPerSample - 8;
> +
> +	/* simple averaging that produces grey RGB values */

Similarly here.

> +	for (unsigned int x = 0; x < width; x++) {
> +		uint16_t value = (in[0] + in[1] + in2[0] + in2[1]) >> 2;
> +		value = value >> shift;
> +		*out++ = value;
> +		*out++ = value;
> +		*out++ = value;
> +		in += 16;
> +		in2 += 16;
> +	}
> +}

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> +
>  void packScanlineRaw10_CSI2P(void *output, const void *input, unsigned int width)
>  {
>  	const uint8_t *in = static_cast<const uint8_t *>(input);
> @@ -321,25 +345,25 @@ const std::map<PixelFormat, FormatInfo> formatInfo = {
>  		.bitsPerSample = 16,
>  		.pattern = { CFAPatternBlue, CFAPatternGreen, CFAPatternGreen, CFAPatternRed },
>  		.packScanline = packScanlineRaw16,
> -		.thumbScanline = thumbScanlineRawXX_CSI2P,
> +		.thumbScanline = thumbScanlineRawXX,
>  	} },
>  	{ formats::SGBRG16, {
>  		.bitsPerSample = 16,
>  		.pattern = { CFAPatternGreen, CFAPatternBlue, CFAPatternRed, CFAPatternGreen },
>  		.packScanline = packScanlineRaw16,
> -		.thumbScanline = thumbScanlineRawXX_CSI2P,
> +		.thumbScanline = thumbScanlineRawXX,
>  	} },
>  	{ formats::SGRBG16, {
>  		.bitsPerSample = 16,
>  		.pattern = { CFAPatternGreen, CFAPatternRed, CFAPatternBlue, CFAPatternGreen },
>  		.packScanline = packScanlineRaw16,
> -		.thumbScanline = thumbScanlineRawXX_CSI2P,
> +		.thumbScanline = thumbScanlineRawXX,
>  	} },
>  	{ formats::SRGGB16, {
>  		.bitsPerSample = 16,
>  		.pattern = { CFAPatternRed, CFAPatternGreen, CFAPatternGreen, CFAPatternBlue },
>  		.packScanline = packScanlineRaw16,
> -		.thumbScanline = thumbScanlineRawXX_CSI2P,
> +		.thumbScanline = thumbScanlineRawXX,
>  	} },
>  	{ formats::SBGGR10_CSI2P, {
>  		.bitsPerSample = 10,

-- 
Regards,

Laurent Pinchart