function getFileInfo, name

	 envi_open_file, name, r_fid=id
	 
	 if id eq -1 then return, {errorstruct, name:name, ns:-1, nl:-1, nb:-1}

	 envi_file_query, id, nb=nb, nl=nl, ns=ns, h_map=maph, descrip=desc, $
	 	interleave=interleave, data_type=type
	 if maph eq -1 then return, {errorstruct, name:name, ns:-1, nl:-1, nb:-1}
	 
	 handle_value, maph, map
	 envi_file_mng, id=id, /remove

	 return, {imagestruct, name:name, ns:ns, nl:nl, nb:nb, map:map, desc:desc, $
	 	interleave:interleave, type:type}
end


function rescale, data, n_percent
	nbands = n_elements(data(0,0,*))-1
	bmin = fltarr(nbands+1)
	bmax = fltarr(nbands+1)
	
	for band = 0, nbands do begin
		img = data(*,*,band)
		hist = histogram(img)
		bmin(band)=0
		i=1
		full = float(n_elements(where(img ne 0)))
		while bmin(band) lt n_percent do begin
			bmin(band)=bmin(band)+hist(i)/full
			i=i+1
		endwhile
		bmin(band) = i-1
		
		bmax(band)=0
		i=255
		while bmax(band) lt n_percent do begin
			bmax(band)=bmax(band)+hist(i)/full
			i=i-1
		endwhile
		bmax(band) = i+1

;; this doesn't actually rescale the image, but it allows tvscl to do a n_percent rescale	
		index = where(img gt bmax(band))
		if index(0) ne -1 then begin
			img(index) = byte(bmax(band))
			print, 'reseting max for band ', band+1
		endif
		
		index = where(img lt bmin(band))
		if index(0) ne -1 then img(index) = byte(bmin(band))
		
		img = img - bmin(band)
		data(*,*,band) = img
	endfor
	return, data
end

pro previewBSQ, greyscale=greyscale, sz=sz, tile=tile, pstrch=pstrch
  envistart
  
  screen=1600-sz
  if not keyword_set(pstrch) then pstrch=0.03
  if not keyword_set(sz) then sz=1000
  window, xsize=sz, ysize=sz
  shrinkfactor = 7.5
  
  j=0
  filelist = findfile('*.bsq')
  for i=0, n_elements(filelist)-1 do begin
     print, filelist(i)
     openr, un, filelist(i), /get
     info = getFileInfo(filelist(i))
     
     data = bytarr(info.ns, info.nl, info.nb)
     readu, un, data
     
;     data = congrid(data, fix(info.ns/shrinkfactor),
;     fix(info.nl/shrinkfactor), info.nb)
     data = congrid(data, sz,sz,info.nb)

     
     if pstrch gt 0.01 then $
       data = rescale(data, pstrch)
     if not keyword_set(greyscale) then begin
        if info.nb ge 3 then begin
           img = data
           img(*,*,0) = data(*,*,2)
           img(*,*,2) = data(*,*,0)
           tvscl,img, true=3, /order
        endif else $
          tvscl, data, /order
     endif else begin

        for j=0, info.nb-1 do begin
           if pstrch lt 0.01 then begin
              print, pstrch
              tv, data[*,*,j],/order 
           endif else tvscl, data[*,*,j], /order
           if keyword_set(tile) and j ne info.nb-1 then window, (i+1)*(j+1), $
             xsize=sz, ysize=sz, xpos=((i+1)*(j+1)*(sz+10))mod screen, $
             ypos=(((i+1)*(j+1)*sz)/screen)*(sz+15) & $
;             print, ((i+1)*(j+1)*sz)/screen, ((i+1)*(j+1)*sz), $
;             ((i+1)*(j+1)*sz) mod screen
        endfor
     endelse
     if keyword_set(tile) and i ne n_elements(filelist)-1 then $
       window, (i+1)*(j+1),xsize=sz, ysize=sz
  endfor
end