program imagereader
	implicit none
	integer, parameter :: maxsize=1000
        integer, parameter :: maxchar=80

	integer, dimension(maxsize,maxsize) :: image1
        integer, dimension(maxsize,maxsize) :: image2
        integer, dimension(100000) :: pixarray, newpixarray
        character(maxchar) :: line ! this is a string, with "dimension" 
                                   ! it's a char array
	integer :: rows, cols
        integer :: row, col, mycol
        integer :: maxpixel
        integer :: newline, diff
        integer :: totalpix, totallines  ! this version: pixperline=1
                                         ! save as pgm with gimp, 
                                         ! automatically has one pixel per line
        integer :: linenum,i, start
        integer time_array_0(8), time_array_1(8)
        real start_time, finish_time

        open(10, file='ISS-four.pgm')
        open(20, file='figtest.pgm')
        read(10,*) line  ! format line
        read(10,*) line  ! comment line
        read(10,*) cols, rows
        read(10,*) maxpixel
        write(*,*) 'Rows=', rows, "Cols=", cols, "Max pixel value=", maxpixel
        totallines = rows*cols
        write(*,*) "Totallines=", totallines
        do row=1,rows
           do col=1,cols
               read(10,*) image1(row,col)
           end do
        end do
        write(*,*) 'Starting image processing...'
        call date_and_time(values=time_array_0)
        start_time = time_array_0 (5) * 3600 + time_array_0 (6) * 60 &
                       + time_array_0 (7) + 0.001 * time_array_0 (8)
        write (6, '(8x, 1a, 1f16.6)') 'begin (date_and_time):  ', &
                         start_time
        do row=1,rows
           do col=1,cols
         !      image2(row,col)= image1(row,col)/3 !int(sqrt(real(image1(row,col))))
               image2(row,col)= image1(row,col) * 1.5
               if (image2(row,col) > 255) then
                   image2(row,col) = 255
               end if
           end do
        end do
        call date_and_time(values=time_array_1)
        finish_time = time_array_1 (5) * 3600 + time_array_1 (6) * 60 &
                       + time_array_1 (7) + 0.001 * time_array_1 (8)
                       
        write(*,*) 'End image processing'
        write (6, '(8x, 1a, 1f16.6)') 'end (date_and_time):    ', &
                   finish_time
        write(*,*) 'Total time=', finish_time - start_time     


        write(20,*) "P2"
        write(20,*) "# Test file"
        write(20,*) cols,rows
        write(20,*) maxpixel
        do row = 1, rows
           do col = 1, cols
               write(20,*) image2(row,col)
           end do
        end do
        close(20)

	end program