https://github.com/6by9/lens_shading

Lens shading analysis tool
https://github.com/6by9/lens_shading

Last synced: 3 months ago
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Lens shading analysis tool

• Host: GitHub
• URL: https://github.com/6by9/lens_shading
• Owner: 6by9
• Created: 2017-08-10T11:25:15.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2021-06-25T16:08:14.000Z (over 3 years ago)
• Last Synced: 2024-04-30T08:33:33.547Z (7 months ago)
• Language: C
• Size: 5.86 KB
• Stars: 20
• Watchers: 8
• Forks: 9
• Open Issues: 3
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-ISP - C

README

        
This app takes a raw or JPEG+raw file created on a Pi and analyses it to create a lens shading table.

The image should be of a well illuminated uniform scene (eg plain white sheet of paper or wall),

as it does a simple comparison of values at the appropriate points to make up a compensation table.

It'll write out the four colour channels as ch1.bin-ch4.bin, viewable as

16bit/pixel single channel images, although only the bottom 10 bits are used.

It also writes a file called ls_table.h, which provides the lens shading grid.

Pass that back to the camera component using code similar to:

```

    {

      MMAL_PARAMETER_LENS_SHADING_T ls = {{MMAL_PARAMETER_LENS_SHADING_OVERRIDE, sizeof(MMAL_PARAMETER_LENS_SHADING_T)}};

      void *grid;

      #include "ls_grid.h"

      ls.enabled = MMAL_TRUE;

      ls.grid_cell_size = 64;

      ls.grid_width = ls.grid_stride = grid_width;

      ls.grid_height = grid_height;

      ls.ref_transform = ref_transform;

      state->lens_shading = vcsm_malloc(ls.grid_stride*ls.grid_height*4, "ls_grid");

      ls.mem_handle_table = vcsm_vc_hdl_from_hdl(state->lens_shading);

      grid = vcsm_lock(state->lens_shading);

      memcpy(grid, ls_grid, vcos_min(sizeof(ls_grid), ls.grid_stride*ls.grid_height*4));

      vcsm_unlock_hdl(state->lens_shading);

      status = mmal_port_parameter_set(camera->control, &ls.hdr);

      if (status != MMAL_SUCCESS)

         vcos_log_error("Failed to set lens shading parameters - %d", status);

   }

```

and

```

      vcsm_free(state.lens_shading);

```

when finished.