00001 function pix_hdr = GE_readHeaderPixel(fid, byte_align)
00002 %
00003 % pix_hdr = read_pixel_header(fid, byte_align)
00004 %
00005 % Loads the pixel header from the file with filed id fid
00006 % and returns it as a structure. 
00007 % if byte_align = 1 then 32-bit alignment (SGI, LX2 format)
00008 % if byte_align = 0 then 16-bit alignment (Sun, 5.X format)
00009 %
00010 % Souheil J. Inati
00011 % Dartmouth College
00012 % May 2000
00013 % souheil.inati@dartmouth.edu
00014 %
00015 
00016 % define the structure and read
00017 pix_hdr = struct('img_magic', fread(fid,1,'int32'));
00018 pix_hdr = setfield(pix_hdr, 'img_hdr_length', fread(fid,1,'int32'));% length of total header in bytes and
00019                                                                     % a byte displacement to the 'pixel data area'  
00020 pix_hdr = setfield(pix_hdr, 'img_width', fread(fid,1,'int32'));  % width (pixels) of image  
00021 pix_hdr = setfield(pix_hdr, 'img_height', fread(fid,1,'int32')); % height (pixels) of image 
00022 pix_hdr = setfield(pix_hdr, 'img_depth', fread(fid,1,'int32'));  % depth (1, 8, 16, or 24 bits) of pixel 
00023 pix_hdr = setfield(pix_hdr, 'img_compress', fread(fid,1,'int32'));   % type of compression; see IC_* below 
00024 pix_hdr = setfield(pix_hdr, 'img_dwindow', fread(fid,1,'int32'));    % default window setting 
00025 pix_hdr = setfield(pix_hdr, 'img_dlevel', fread(fid,1,'int32')); % default level setting 
00026 pix_hdr = setfield(pix_hdr, 'img_bgshade', fread(fid,1,'int32'));    % background shade to use for non-image 
00027 pix_hdr = setfield(pix_hdr, 'img_ovrflow', fread(fid,1,'int32'));    % overflow value 
00028 pix_hdr = setfield(pix_hdr, 'img_undflow', fread(fid,1,'int32'));    % underflow value 
00029 pix_hdr = setfield(pix_hdr, 'img_top_offset', fread(fid,1,'int32')); % number of blank lines at image top 
00030 pix_hdr = setfield(pix_hdr, 'img_bot_offset', fread(fid,1,'int32')); % number of blank lines at image bottom 
00031 pix_hdr = setfield(pix_hdr, 'img_version', fread(fid,1,'int16'));    % version of the header structure
00032 if byte_align, fseek(fid,2,0); end % 32-bit alignment
00033 pix_hdr = setfield(pix_hdr, 'img_checksum', fread(fid,1,'uint16')); % 16 bit end_around_carry sum of pixels 
00034 pix_hdr = setfield(pix_hdr, 'img_p_id', fread(fid,1,'int32'));   % a byte disp to unique image identifier 
00035 pix_hdr = setfield(pix_hdr, 'img_l_id', fread(fid,1,'int32'));   % byte length of unique image identifier 
00036 pix_hdr = setfield(pix_hdr, 'img_p_unpack', fread(fid,1,'int32'));   % a byte disp to 'unpack control' 
00037 pix_hdr = setfield(pix_hdr, 'img_l_unpack', fread(fid,1,'int32'));   % byte length of 'unpack control' 
00038 pix_hdr = setfield(pix_hdr, 'img_p_compress', fread(fid,1,'int32')); % a byte disp to 'compression control' 
00039 pix_hdr = setfield(pix_hdr, 'img_l_compress', fread(fid,1,'int32')); % byte length of 'compression control' 
00040 pix_hdr = setfield(pix_hdr, 'img_p_histo', fread(fid,1,'int32'));    % a byte disp to 'histogram control' 
00041 pix_hdr = setfield(pix_hdr, 'img_l_histo', fread(fid,1,'int32'));    % byte length of 'histogram control' 
00042 pix_hdr = setfield(pix_hdr, 'img_p_text', fread(fid,1,'int32')); % a byte disp to 'text plane data' 
00043 pix_hdr = setfield(pix_hdr, 'img_l_text', fread(fid,1,'int32')); % byte length of 'text plane data' 
00044 pix_hdr = setfield(pix_hdr, 'img_p_graphics', fread(fid,1,'int32')); % a byte disp to 'graphics plane data' 
00045 pix_hdr = setfield(pix_hdr, 'img_l_graphics', fread(fid,1,'int32')); % byte length of 'graphics plane data' 
00046 pix_hdr = setfield(pix_hdr, 'img_p_dbHdr', fread(fid,1,'int32'));    % a byte disp to 'data base header data' 
00047 pix_hdr = setfield(pix_hdr, 'img_l_dbHdr', fread(fid,1,'int32'));    % byte length of 'data base header data' 
00048 pix_hdr = setfield(pix_hdr, 'img_levelOffset', fread(fid,1,'int32'));% value to add to stored Pixel Data values
00049                                                                      % to get the correct presentation value 
00050 pix_hdr = setfield(pix_hdr, 'img_p_user', fread(fid,1,'int32')); % byte displacement to user defined data 
00051 pix_hdr = setfield(pix_hdr, 'img_l_user', fread(fid,1,'int32')); % byte length of user defined data 
00052  
00053 return