How to access struct values

I am using Phill Salee's jpeg toolbox. Link http://dde.binghamton.edu/download/jpeg_toolbox.zip

im=jpeg_read('baboon.jpg')

im =

          image_width: 512
         image_height: 512
     image_components: 3
    image_color_space: 2
      jpeg_components: 3
     jpeg_color_space: 3
             comments: {}
          coef_arrays: {[512x512 double]  [256x256 double]  [256x256 double]}
         quant_tables: {[8x8 double]  [8x8 double]}
       ac_huff_tables: [1x2 struct]
       dc_huff_tables: [1x2 struct]
      optimize_coding: 0
            comp_info: [1x3 struct]
     progressive_mode: 0

When I run the line given below I get "Reference to non-existent field 'coef_arraysim'" error!

Xy = im.coef_arraysim.comp_info(1).component_id ;

How do I get the type of output shown below? The below shown output is for some other image and not baboon.jpeg.

>> whos Xy

Name Size Bytes Class Attributes

Xy 248x184 365056 double

Answer 1

[OCDER]

There is no coef_arraysim field in im, hence the error message.

I do see something close, coef_arrays, which stores 3 double matrices. To access one of the double matrix within im.coef_arrays, do this:

Xy = im.coef_arrays{N}  %where N is 1, 2, or 3