Transcript Graphics and Still Images John H. Krantz Hanover College Outline  Background  Images  File Types  Acquiring  Using ImageJ  Basics  Advanced.

Graphics and Still Images
John H. Krantz
Hanover College
Outline
 Background
 Images
 File Types
 Acquiring
 Using ImageJ
 Basics
 Advanced
The General Beast
Screen Mosaic Triad
Arrangement
Interlaced Projection
The Electron Beam
0.5
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0.1
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Seeing the Flicker
Graphics vs. Images
 Some definitions: mine for clarity here:
 Graphics Def: computer generated or drawn
by you.
 Image: scanned, captured, take photograph
or an graphic file not generated by you.
 Difference:
 In a graphic, you can directly manipulate the
elements because you drew them – Sprites
 In an image, you can manipulate pixels but not
directly the elements. This has a great impact.
Images or Graphics on the Screen
 Pixels: smallest picture element
 Pixels are not screen dots!!!
 Several dots (at least three, one of each color) make
up each pixel)
 Bitmat: An array of information that contains the
information for the image.
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It is a 3 dimensional array
Width x Height x 24 (8 for each color)
So can be huge
(.bmp and .tif or .tiff are most common bitmaps)
Graphic and Image Formats
 Bitmap (bmp, PCT, Tiff) – big, not good for
web
 Graphic Interchange Format (Gif) can animate
 8 bits of color – palette or lookup table or LUT –
no loss of spatial information
 Can be some legal issues – make sure the
generator legally can generate GIF’s
 Generally best compression for simple graphics –
bad for photos
 Can generate transparent regions
 Can Animate
Graphics and Image Formats
 JPG
 Generally better for images and photos
 Spatial not color compression, can distort image
spatially and more loss with each save
 Now can animate as well.
Example JPG
BMP vs JPEG File Sizes
Both images are the same relative size.
.BMP
900kb
.JPEG High Quality ~700kb
ImageJ
 Free at: http://rsb.info.nih.gov/ij/index.html
 Overview
 Java program
 Interface a bit awkward because it is free
 Expandable via plug-ins
 Covers all basic editing and many advanced very advanced
 Scientific quality image editor
 Used in many technical applications
Basic ImageJ Interface
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Menus and Tool bars
File Open, Save, Save As, Revert
Edit Cut, Copy, Paste, Selection, Options
Image Basic Image Editing
Process More Advanced Image Editing Options
Shapes are for selection or drawing. The “A” is
for adding text.
File/Open
File/New
Drawing with ImageJ
 Very simple but easy
 Access to pixels
 No anti-aliasing in most drawing modes
 Downside: jaggies
 Upside: in complete control of graphics
 Can store and edit in lots of formats
Aliasing
 Technical definition:
 When an image contains frequencies beyond the
range of the sampling matrix, the wrap-around and
occur as lower frequencies, distorting the image
Aliasing
 Description of aliasing
 Generally try to draw and image that has
too fine of detail or sharp edges
 Causes “jaggies”
 And pixel artifacts
 That is you can notice the pixels
Aliasing and Pixel
Effects
Try some
 When open in ImageJ, all images are bitmaps,
but can be edited in different types
 Basic Graphics Objects
 Adding Text
 Saving in Different Format
 File/Save As
Putting a Graphic in a Webpage
 <p align="center"><img border="0"
src=“imagename.gif" width="170"
height="238“ alt = “ATI Image”></p>
Acquiring
 Scanning
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Flatbed gives best quality.
Use 35 MM film for pictures – best resolution
Scan at a high level and sample down later
Any model seems good this day.
Scanned Image
Digital Cameras
 No loss in Scanning
 CCD
 3.1 Megapixel at least if need photo quality
and larger
 there are 5 megapixel
 Can use lower image if only need web
 But do not sacrifice image quality
 Easy to download
 Can be good in low light
Low Light Digital Image
Taking Photos Digitally
 Focusing: Automatic and Manual
 Regular focus
 Macro – allows focusing up close
 Spot Focus: focus is determined by point
 Shutter Speed
 Zoom:
 Do not use digital zoom – if need more zoom, do
it on computer later
 On my default is off except for movies
Taking Pictures (cont.)
 White Balance, controls for our color
constancy
 Effect of the Illuminant
 Flash:
 often I keep it off.
 Image Size:
 I keep at standard (full pixel density, some
JPG compression). Balance between image
quality and ability to store on disk ~ 1
Meg/picture
Use of Flash
Flash
No Flash
Watch for reflections. Can get inexpensive table camera tripods.
Basic Editing in ImageJ
 Edit a bitmap
 Most Important Command: Revert
 Under the File Menu
 Takes back to last save – careful with saves.
 Ctrl-z is undo but only one step.
 Suggest do “save as” or make copy first so
don’t destroy original
 Resize for web: under Image: Scale or
Image/Adjust: Size
Basic Editing
 Often starts with selecting a region
 Most editing will then occur defined by the
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selection
Edit/Clear
Edit/Clear Outside
Image/Crop
Image/Adjust/Brightness and Contrast
Edit/Clear
Edit/Clear Outside
Cropping or my Thumb got in the
way – well not really
Select Area Select square on Tool
Box
Cropped Image – What thumb?
Under Image Menu: Crop
Adjusting Rotating – Image Menu/
Rotate
Brightness and Contrast
Image/Adjust/Brightness and
Contrast
An Example
 How symmetrical am
I?
 The original image
Select the region
 I used the rectangular
region – easier
 Centered on some
feature in middle –
find the x value (I
used a gap in my
teeth)
 Then use Copy from
the Edit menu or
CTRL-c
Flip and Paste
Image/Rotate
Flip Horizontally
Edit/Paste or CTRL-V
Final Picture
 After adjust location
Paste Control
 Copy
 Blend
Paste Control
 Difference
 Transparent
Converting Images
 Save as for Image Types – use GIF or
JPG
 Must add extension, it is not added
automatically
 Always use save as to save anything other
than a TIFF
 This is a full color uncompressed image
Converting Images
 Converting Color Depth or to Grayscale
image
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Under Image Menu/Type
8-bit, 16-bit, 32-bit are grayscale
8-bit RGB and RGB are color
It is not possible to arbitrarily convert images
 but ImageJ gives table of possible conversions
 e.g. can only convert JPG to and 8bit grayscale.
Adding to Images
 Setting Colors
 Edit: Options: Foreground Color
 Image: Colors
 Adding Text
 Set font in
 Edit: Options: Font
 Draws in selected color
Adding to Images
 Drawing a basic graphics object
 Draw width:
 Edit: Options: Line Width
 Select shape
 Put shape on image
 Edit: Draw or ctrl-D
 Filled regions
 Same as above, but:
 line width not important
 Use Edit: Fill or ctrl-F
Filtering Images
 Under the Process menu
 Sharpen: more edges
 Smooth: dull details
Filtering Images
 Edges: finds them –
so type of outline
Filtering Images
 Gaussian: blurs
 Amount of blur
depends upon the
standard deviation
(called radius)
Plugins
 These are the heart and sole of ImageJ
 Some have limits but as developments go on,
you will be able to get new ones without these
limits
 How to get: http://rsb.info.nih.gov/ij/plugins/
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Pick desired plug in.
Go to ImageJ folder, then to plugins folder
I suggest making folders under this to keep organized
Restart ImageJ
More on Plugins
 Can build your own
 Most built by users
 Uses Java
 instructions on web page
 Some good examples
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RGB Recolor
Inverter
File opener: multiple files
AVI writer
Color Chooser or Color Picker
Creating Shortcuts
 Under Plugins menu
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Pick Shortcuts
Then Create Shortcut
Lists all commands
Type letter that will be matched with control
button.
 Under Plugins/Utilities/Shortcuts will show all
current shortcuts
Adding Shortcuts Example
 Pick command JPEG
 This saves files in a jpeg format
 A pain to get to usually
 Use “J”
 Try ctrl-J
Mail List
 http://rsb.info.nih.gov/ij/list.html
 Active community of people developing
 They are very tolerant of idiotic questions.
I have personal experience of their
tolerance
Assignment
 Take series of images that you might want
shown in sequences as part of a study