GE_readHeaderPixel

 pix_hdr = read_pixel_header(fid, byte_align)

 Loads the pixel header from the file with filed id fid
 and returns it as a structure. 
 if byte_align = 1 then 32-bit alignment (SGI, LX2 format)
 if byte_align = 0 then 16-bit alignment (Sun, 5.X format)

 Souheil J. Inati
 Dartmouth College
 May 2000
 souheil.inati@dartmouth.edu

0001 function pix_hdr = GE_readHeaderPixel(fid, byte_align)
0002 %
0003 % pix_hdr = read_pixel_header(fid, byte_align)
0004 %
0005 % Loads the pixel header from the file with filed id fid
0006 % and returns it as a structure.
0007 % if byte_align = 1 then 32-bit alignment (SGI, LX2 format)
0008 % if byte_align = 0 then 16-bit alignment (Sun, 5.X format)
0009 %
0010 % Souheil J. Inati
0011 % Dartmouth College
0012 % May 2000
0013 % souheil.inati@dartmouth.edu
0014 %
0015 
0016 % define the structure and read
0017 pix_hdr = struct('img_magic', fread(fid,1,'int32'));
0018 pix_hdr = setfield(pix_hdr, 'img_hdr_length', fread(fid,1,'int32'));% length of total header in bytes and
0019                                                                     % a byte displacement to the 'pixel data area'
0020 pix_hdr = setfield(pix_hdr, 'img_width', fread(fid,1,'int32'));  % width (pixels) of image
0021 pix_hdr = setfield(pix_hdr, 'img_height', fread(fid,1,'int32')); % height (pixels) of image
0022 pix_hdr = setfield(pix_hdr, 'img_depth', fread(fid,1,'int32'));  % depth (1, 8, 16, or 24 bits) of pixel
0023 pix_hdr = setfield(pix_hdr, 'img_compress', fread(fid,1,'int32'));   % type of compression; see IC_* below
0024 pix_hdr = setfield(pix_hdr, 'img_dwindow', fread(fid,1,'int32'));    % default window setting
0025 pix_hdr = setfield(pix_hdr, 'img_dlevel', fread(fid,1,'int32')); % default level setting
0026 pix_hdr = setfield(pix_hdr, 'img_bgshade', fread(fid,1,'int32'));    % background shade to use for non-image
0027 pix_hdr = setfield(pix_hdr, 'img_ovrflow', fread(fid,1,'int32'));    % overflow value
0028 pix_hdr = setfield(pix_hdr, 'img_undflow', fread(fid,1,'int32'));    % underflow value
0029 pix_hdr = setfield(pix_hdr, 'img_top_offset', fread(fid,1,'int32')); % number of blank lines at image top
0030 pix_hdr = setfield(pix_hdr, 'img_bot_offset', fread(fid,1,'int32')); % number of blank lines at image bottom
0031 pix_hdr = setfield(pix_hdr, 'img_version', fread(fid,1,'int16'));    % version of the header structure
0032 if byte_align, fseek(fid,2,0); end % 32-bit alignment
0033 pix_hdr = setfield(pix_hdr, 'img_checksum', fread(fid,1,'uint16')); % 16 bit end_around_carry sum of pixels
0034 pix_hdr = setfield(pix_hdr, 'img_p_id', fread(fid,1,'int32'));   % a byte disp to unique image identifier
0035 pix_hdr = setfield(pix_hdr, 'img_l_id', fread(fid,1,'int32'));   % byte length of unique image identifier
0036 pix_hdr = setfield(pix_hdr, 'img_p_unpack', fread(fid,1,'int32'));   % a byte disp to 'unpack control'
0037 pix_hdr = setfield(pix_hdr, 'img_l_unpack', fread(fid,1,'int32'));   % byte length of 'unpack control'
0038 pix_hdr = setfield(pix_hdr, 'img_p_compress', fread(fid,1,'int32')); % a byte disp to 'compression control'
0039 pix_hdr = setfield(pix_hdr, 'img_l_compress', fread(fid,1,'int32')); % byte length of 'compression control'
0040 pix_hdr = setfield(pix_hdr, 'img_p_histo', fread(fid,1,'int32'));    % a byte disp to 'histogram control'
0041 pix_hdr = setfield(pix_hdr, 'img_l_histo', fread(fid,1,'int32'));    % byte length of 'histogram control'
0042 pix_hdr = setfield(pix_hdr, 'img_p_text', fread(fid,1,'int32')); % a byte disp to 'text plane data'
0043 pix_hdr = setfield(pix_hdr, 'img_l_text', fread(fid,1,'int32')); % byte length of 'text plane data'
0044 pix_hdr = setfield(pix_hdr, 'img_p_graphics', fread(fid,1,'int32')); % a byte disp to 'graphics plane data'
0045 pix_hdr = setfield(pix_hdr, 'img_l_graphics', fread(fid,1,'int32')); % byte length of 'graphics plane data'
0046 pix_hdr = setfield(pix_hdr, 'img_p_dbHdr', fread(fid,1,'int32'));    % a byte disp to 'data base header data'
0047 pix_hdr = setfield(pix_hdr, 'img_l_dbHdr', fread(fid,1,'int32'));    % byte length of 'data base header data'
0048 pix_hdr = setfield(pix_hdr, 'img_levelOffset', fread(fid,1,'int32'));% value to add to stored Pixel Data values
0049                                                                      % to get the correct presentation value
0050 pix_hdr = setfield(pix_hdr, 'img_p_user', fread(fid,1,'int32')); % byte displacement to user defined data
0051 pix_hdr = setfield(pix_hdr, 'img_l_user', fread(fid,1,'int32')); % byte length of user defined data
0052  
0053 return