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Image Data and Display. For Class Consistency. % source ~rvrpci/.simg726.rc. Quiz #2 Topics. mkdir chmod cd grep ci and co. PBMPLUS FORMAT and xv. Digital image format concepts PBMPLUS image interchange format. Displaying digital image xv image display. PBMPLUS Image Data Types. - PowerPoint PPT Presentation
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Rolando V. Raqueño Thursday, April 20, 202311
Image Data and Display
Rolando V. Raqueño Thursday, April 20, 202322
For Class Consistency
% source ~rvrpci/.simg726.rc
Rolando V. Raqueño Thursday, April 20, 202333
Quiz #2 Topics
• mkdir• chmod• cd• grep• ci and co
Rolando V. Raqueño Thursday, April 20, 202344
PBMPLUS FORMAT and xv• Digital image format concepts
– PBMPLUS image interchange format.
• Displaying digital image– xv image display
Rolando V. Raqueño Thursday, April 20, 202355
PBMPLUS Image Data Types• Bilevel Image Data Type
– Black and White
• Monochrome Image Data Type– Greyscale
• RGB Color Image Data Type – Color
Rolando V. Raqueño Thursday, April 20, 202366
Two PBMPLUS Representations
• All PBMPLUS data formats have the following representations– ASCII Format
• (for Human Consumption)
– RAW Format • (for Computer Consumption)
Rolando V. Raqueño Thursday, April 20, 202377
Displaying Images• Use xv utility for display and documentation purposes.
– Note that xv is an X client
• Should NEVER be used for image processing – USE ONLY FOR DISPLAY PURPOSES
• To invoke xv
% xv &% xv filename.pgm &
Rolando V. Raqueño Thursday, April 20, 202388
Portable Bit Map (PBM)
• Bilevel Image Data Type – (Black and White)
• Used to represent printed black and white imagery such as documents and faxes.
• Uses 0’s (zeroes) to represent white – (no ink deposited on paper)
• Uses 1’s (ones) to represent black – (ink deposited on paper)
Rolando V. Raqueño Thursday, April 20, 202399
Let us digress – The vi Problem
• vi practice and creation of a bilevel image.• 7”x10” graph paper divided into 10 squares per inch. • Cell not covered by ink
– value of zero (0).
• Cell fully or partially covered by ink – value of one (1).
• You will have a total of 700 pixels to enter.
Rolando V. Raqueño Thursday, April 20, 20231010
Problem #1 Solution
• vi - Brute Force Solution1. Is the current pixel 0 (zero) or 1 (one)?
2. Type the appropriate character
3. Repeat steps 1 and 2 until done
Rolando V. Raqueño Thursday, April 20, 20231111
Problem #1 Solution
• vi- Smart Solution1. Type the vi command “70i0” “seventy, i - for insert, 0 (zero)”
2. Hit the ESCAPE key to get you out of insert mode.3. Type the vi command “o” to open a new line4. Hit the ESCAPE key to get you out of insert mode.5. Move back up to the line of zeroes and use the yy
(yank command) to make a copy of the line of 70 zeroes.
Rolando V. Raqueño Thursday, April 20, 20231212
Problem #1 Solution
• vi- Smart Solution6. Type the vi command “p” 10 times
7. Move back up to the top line of zeroes and use the 10yy (yank command) to make a copy of 10 lines of 70 zeroes per line.
8. Type the vi command “p” 10 times
9.You will now have a page of 700 zeroes.
Rolando V. Raqueño Thursday, April 20, 20231313
Problem #1 Solution• vi- Smart Solution
10. You can navigate to the areas that need to be changed to “1” and use the “R” command to replace contiguous set of characters.
11. Hit the ESCAPE key to get you out of insert mode.12. Navigate to next section and repeat steps 10 -12
until done.13. Save the file out and exit vi
:wq signature.dat
Rolando V. Raqueño Thursday, April 20, 20231414
Yet another vi Digression
• To show line number in vi, execute the following command
:set number• To disable line numbers in vi, execute
the following command
:set nonumber
Rolando V. Raqueño Thursday, April 20, 20231515
Viewing current vi settings:set allnoautoindent nomodelines noshowmode
autoprint nonumber noslowopen
noautowrite nonovice tabstop=8
nobeautify nooptimize taglength=0
directory=/var/tmp paragraphs=IPLPPPQPP LIpplpipnpbtags=tags /usr/lib/tags
noedcompatible prompt tagstack
noerrorbells noreadonly term=vt220
noexrc redraw noterse
flash remap timeout
hardtabs=8 report=5 ttytype=vt220
noignorecase scroll=11 warn
nolisp sections=NHSHH HUuhsh+c window=23
nolist shell=/bin/csh wrapscan
magic shiftwidth=8 wrapmargin=0
mesg noshowmatch nowriteany
Rolando V. Raqueño Thursday, April 20, 20231616
Saving vi Preferences
• Preferences such as :set number can be saved in the file .exrc in your home directory (~)
Rolando V. Raqueño Thursday, April 20, 20231717
A vi Command to Always Remember
• To replace all occurrences or a string in a file with new string.:%s/string1/string2/g
OR
:%s/string1/string2/gc(Will ask you for confirmation)
Rolando V. Raqueño Thursday, April 20, 20231818
The Super-smart Solution
• In UNIX
% repeat 70 echo -n 0 >> one_line; echo >> one_line; repeat 100 cat one_line >> signature.dat
Rolando V. Raqueño Thursday, April 20, 20231919
Let’s Create another image
• Put the signature.dat away for the time being and create a simpler image
• Call it bilevel.pbm
Rolando V. Raqueño Thursday, April 20, 20232020
Portable Bit Map (PBM)• Bilevel Image Data Type
– For the ASCII file format, the file header is given by P1 – width and height of the image. – Comments are indicated by the # character
P1# This is a 16 column x 3 row# PBM ASCII image# Created by using vi16 3001010100011010000111110010010000101001001011100
Rolando V. Raqueño Thursday, April 20, 20232121
Portable Bit Map (PBM)• Make a copy of bilevel.pbm and edit the copy to look like
the following,
P1
#This is a 16 column x 3 row PBM ASCII
#image
#
16 3
0010101000110100
0011111001001000
0101001001011100
Rolando V. Raqueño Thursday, April 20, 20232222
Portable Bit Map (PBM)• When displayed looks like
P1
# This is a 16 column x 3 row PBM ASCII
# image
#
16 3
0010101000110100
0011111001001000
0101001001011100
Rolando V. Raqueño Thursday, April 20, 20232323
How to Add a PBMPLUS Header to an Image File
• If its an ASCII file you can use vi• Use the cat command to concatenate a
header from a file or the keyboard (standard input - stdio)
Rolando V. Raqueño Thursday, April 20, 20232424
Put a header on signature.dat and display in xv
• Method #1– Using a text editor, input the appropriate
header values.
Rolando V. Raqueño Thursday, April 20, 20232525
Put a header on signature.dat and display in xv
• Method #2– Edit a file called header.dat containing
the header information– Concatenate the header file at the
beginning of signature.dat using the cat command
% cat header.dat signature.dat > signature.pbm
Rolando V. Raqueño Thursday, April 20, 20232626
Put a header on signature.dat and display in xv
• Method #3– Concatenate the header data from the keyboard
directly to the beginning of signature.dat using the cat command
% cat - signature.dat > signature.pbm
P1
70 100
^D
Rolando V. Raqueño Thursday, April 20, 20232727
Portable Bit Map (PBM)
• There is also a binary version of the PBM image type which uses a P4 header such as the one below
P4
# This is a 16 column x 3 row PBM RAW
# image
16 3
*4>HR\
Rolando V. Raqueño Thursday, April 20, 20232828
Portable Grey Map (PGM)
• Monochrome Image Data Type (Greyscale)– Displayed greyscale imagery– Grey values brightness.– Convention opposite that of the PBM
format
Rolando V. Raqueño Thursday, April 20, 20232929
Portable Grey Map (PGM)
• Monochrome Image Data Type (Greyscale)– EXAMPLE,
P2
# This is a 3 column x 2 row PGM ASCII image
# With a possible maximum grey value of 255
3 2
255
42 52 62
72 82 92
Rolando V. Raqueño Thursday, April 20, 20233030
Portable Grey Map (PGM)
• When displayed, the image is shown below P2
# This is a 3 column x 2 row PGM ASCII image
# With a possible maximum grey value of 255
3 2
255
42 52 62
72 82 92
Rolando V. Raqueño Thursday, April 20, 20233131
Portable Grey Map (PGM)
• There is also a binary version of the PGM image type which uses a P5 header such as the one below
P5
# This is a 3 column x 2 row PGM Raw
# image
3 2
255
*4>HR\
Rolando V. Raqueño Thursday, April 20, 20233232
Portable Pixel Map (PPM)
• RGB Color Image Data Type (Color)– Red, Green, and Blue bands– Arranged in pixel-interleaved format or
band interleaved by pixel (BIP)
Rolando V. Raqueño Thursday, April 20, 20233333
Portable Pixel Map (PPM)• RGB Color Image Data Type (Color)
– For the ASCII file format, • P3 • width, height• maximum grey level possible of the image
– The pixel values are given as a triple representing the red, green, and blue components .
Rolando V. Raqueño Thursday, April 20, 20233434
Portable Pixel Map (PPM)
• RGB Color Image Data Type (Color)– EXAMPLE,
P3
3 3
255
255 0 0 0 255 0 0 0 255
128 0 0 0 128 0 0 0 128
0 0 0 128 128 128 255 255 255
Rolando V. Raqueño Thursday, April 20, 20233535
PPM QUESTION
So what does the data
*4>HR\ look like as a
Raw PPM Image?
Rolando V. Raqueño Thursday, April 20, 20233636
Conversion of Raw Files to PBMPLUS Format
• Alternative to manually prepending a header file using cat command rawtopbm, rawtopgm, or rawtoppm
% rawtopgm 256 256 ~rvrpci/pub/MyCat_P5.raw > MyCat.pgm
Rolando V. Raqueño Thursday, April 20, 20233737
Usage Note About PBMPLUS Commands
• PBMPLUS commands heavily use the UNIX redirection and piping
• To get help use -h option.% rawtopgm -h
usage: rawtopgm [-headerskip N] [-rowskip N] [-tb|-topbottom] [<width> <height>][rawfile]
Rolando V. Raqueño Thursday, April 20, 20233838
Converting PNM Image File to Another Format
• PNM is a generic designator for all PBM, PGM, and PPM
• Convert a PBMPLUS format file into a TIFF – e.g., signature.pbm to signature.tiff.
• Use the following command
% pnmtotiff -none signature.pbm > signature.tiff
-none option means not invoke LZW image compression.
Rolando V. Raqueño Thursday, April 20, 20233939
Rudimentary Image Processing Using the PBMPLUS Utilities
• Requires that all input be in some form of PBM, PGM, PPM image
• Supposed we wanted to enlarge a tiff file ( e.g., signature.tiff) by a scale factor of 2x and then convert it to a SUN raster file.
TIFF TIFF FILEFILE
PNM PNM FILEFILE
2X 2X ScaleScale
PNM PNM FILEFILE
RAST RAST FILEFILE
Rolando V. Raqueño Thursday, April 20, 20234040
Rudimentary Image Processing Using the PBMPLUS Utilities
• The previous process can actually be executed in one UNIX command
% tifftopnm signature.tiff | pnmscale 2.0 | pnmtorast > signature.rast
• In fact you can pipe the information directly to xv before writing it out to another format
% tifftopnm signature.tiff | pnmscale 2.0 | pnmtorast | xv -
Rolando V. Raqueño Thursday, April 20, 20234141
PBMPLUS File Information
• Supposed you wanted to know what the characteristics are of a particular PBMPLUS file you can give the following command% pnmfile MyCat.pgmMyCat.pgm: PGM raw, 256 by 256 maxval 255
Rolando V. Raqueño Thursday, April 20, 20234242
PBMPLUS Histogram Utilities
• Greyscale histogram pgmhist
• Color histogram ppmhist
Rolando V. Raqueño Thursday, April 20, 20234343
Cutting out regions of interest
% pnmcutusage: pnmcut x y width height [pnmfile]
% pnmcropusage: pnmcrop [-white|-black] [-left] [-right] [-top] [-bottom] [pnmfile]
Rolando V. Raqueño Thursday, April 20, 20234444
Pasting or Arranging Images
% pnmcatpnmcat [-white|-black] -leftright|-lr [-jtop|-jbottom] pnmfile pnmfile ...
% pnmpastepnmpaste [-replace|-or|-and |xor] frompnmfile x y [intopnmfile]
Rolando V. Raqueño Thursday, April 20, 20234545
You have a bunch of images...
% pnmindexpnmindex [-size N] [-across N]
[-colors N] [-black] pnmfile ...
Rolando V. Raqueño Thursday, April 20, 20234646
Color Bands Combination and Extraction
% rgb3ppmrgb3toppm redpgmfile greenpgmfile bluepgmfile
% ppmtorgb3ppmtorgb3 [ppmfile]
•results in .red .grn .blu
Rolando V. Raqueño Thursday, April 20, 20234747
Spatial Operations
• pnmconvol• pnmscale• pnmrotate• pnmflip• pnmshear
Rolando V. Raqueño Thursday, April 20, 20234848
Greyscale/Color Operations
• ppmquant• pnmdepth• ppmdither
Rolando V. Raqueño Thursday, April 20, 20234949
Really Useful Stuff
• Doing Screen Captures under X
% xwd | xwdtopnm | pnmdepth 255 | pnmtotiff > screen.tif
• Your cursor will turn into crosshairs
• Click on the window you want to capture
Rolando V. Raqueño Thursday, April 20, 20235050
Screen Capture through xv
• Click on grab button• Specify a time delay• Left button grabs
window• Middle button grabs
a rectangle• Right button cancels
Rolando V. Raqueño Thursday, April 20, 20235151
Getting Hardcopy Output• Determining what type of display device you
haveIDL> help,/deviceAvailable graphics_devices: CGM HP MAC NULL PCL PS ZCurrent graphics device: MAC Macintosh Quickdraw Driver Screen Resolution: 640x442 Physical Color Map Entries (Used / Total): 220 / 256 Current Window Number: 0, size: (320,240) type: Window. Graphics Function: 3 (copy) Current Font: Chicago Default Backing Store: Pixmap. Window Status: 0: Window 320x240 (Retained)
Rolando V. Raqueño Thursday, April 20, 20235252
Getting Hardcopy Output• To get a postscript output of your plot
IDL> set_plot,’ps’IDL> device, Filename=‘new_plot.ps’IDL> plot, my_data,Title=‘Imaging Lab 1’IDL> device, /closeIDL> $lpr -Pdip new_plot.ps
• You then want to return your output device to whatever display device you had originallyIDL> set_plot,’MAC’
Rolando V. Raqueño Thursday, April 20, 20235353
Check Your Postscript File Before Sending to the Printer • You can use the ghostview utility to
view a postscript file
Rolando V. Raqueño Thursday, April 20, 20235454
Note Well
• Always make sure that the printer to which you will be sending your job is capable of talking Postscript. If it does not, you will be killing many trees.
• To find out the status of your job% lpq -P(printer name)
• To kill a print job% lprm -P(printer name) job_number
Rolando V. Raqueño Thursday, April 20, 20235555
Getting Encapsulated Postscript File (EPS)
• To get a postscript file of your plot that you can include into another documentIDL> set_plot,’ps’IDL> device, /encapsulated, /previewIDL> device, Filename=‘new_plot.eps’IDL> plot, my_data,Title=‘Imaging Lab 1’IDL> device, /close
• The above process creates what is known as an Encapsulated Postscript File (EPS)
Rolando V. Raqueño Thursday, April 20, 20235656