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Graphics and Still Images John H. Krantz Hanover College Outline Graphics Types Developing with Paint Images File Types Acquiring Using ImageJ Basics Advanced Graphics vs. Images Some definitions: mine for clarity here: Graphics Def: computer generated or drawn by you.

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Graphics and still images l.jpg

Graphics and Still Images

John H. Krantz

Hanover College


Outline l.jpg
Outline

  • Graphics

    • Types

    • Developing with Paint

  • Images

    • File Types

    • Acquiring

    • Using ImageJ

      • Basics

      • Advanced


Graphics vs images l.jpg
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.


Graphic types l.jpg
Graphic Types

  • Storing Formats:

    • Bitmap (bmp, PCT, Tiff) – big, not good for web

    • Compressed

      • Graphic Interchange Format (Gif) can animate

        • 8 bits of color – palette – no spatial compression

        • Can be some legal issues – make sure the generator legally can generate GIF’s

        • Generally best compression for simple graphics

        • Can generate transparent regions

      • JPG

        • Generally better for images and photos

        • Spatial not color compression, can distort image spatially.

        • Now can animate as well.


Developing with imagej l.jpg
Developing with ImageJ

  • Free

  • Very simple but easy

  • Access to pixels

  • No anti-aliasing

    • Downside: jaggies

    • Upside: in complete control of graphics

  • Can store in Lots of Formats


Try some l.jpg
Try some

  • Basic Graphics Objects

  • Cutting and Pasting

    • Transparency

  • Adding Text

  • Saving in Different Format

    • Transparency (set in web page program).

  • Reading Different Formats


Image types l.jpg
Image Types

  • Same as with graphics

  • JPG is generally better in terms of compression ratio, smaller files, for images

  • For complex images, minor spatial distortions will be hidden.



Acquiring l.jpg
Acquiring

  • Scanning

    • 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.



Digital cameras l.jpg
Digital Cameras

  • No loss in Scanning

  • CCD

  • 3.1 Megapixel at least if need photo quality

    • there are 5 megapixel

    • Can use lower quality if only need web.

  • Easy to download

  • Good in low light



Taking photos digitally l.jpg
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 l.jpg
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 l.jpg
Use of Flash

Flash No Flash


Editing images with imagej l.jpg
Editing Images with ImageJ

  • Free at: http://rsb.info.nih.gov/ij/index.html

  • Overview

    • Java program

    • Interface a bit awkward because not free (no shortcuts)

    • Expandable via plug-ins

  • Covers all basic editing and many advanced


Basic editing l.jpg
Basic Editing

  • Most Important Command: Revert

    • Under the File Menu

    • 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 Adjust: Size


Basic editing18 l.jpg
Basic Editing

  • Selecting a region

  • Clear

  • Clear outside

  • Cropping

  • Rotating and Flipping

  • Adjusting Brightness and Contrast

  • Thresholding


An example l.jpg
An Example

  • How symmetrical am I?

    • The original image


Select the region l.jpg
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)


Crop and flip l.jpg

Cropped

Flipped Horizontally

Crop and Flip


Cut and paste l.jpg
Cut and Paste

Final Picture

  • Reopen original face

  • Select all of half face

  • Paste into other

  • Adjust location


Paste control l.jpg
Paste Control

  • Copy

  • Blend


Paste control24 l.jpg
Paste Control

  • Difference

  • Transparent


Converting images l.jpg
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 images26 l.jpg
Converting Images

  • Converting Color Depth or to Grayscale image

    • 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 l.jpg
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 images28 l.jpg
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 l.jpg
Filtering Images

  • Under the Process menu

    • Sharpen: more edges

    • Smooth: dull details


Filtering images30 l.jpg
Filtering Images

  • Edges: finds them – so type of outline


Filtering images31 l.jpg
Filtering Images

  • Gaussian: blurs

    • Amount of blur depends upon the standard deviation (called radius)


Some useful plugins l.jpg
Some Useful Plugins

  • Some have limits but as developments go, you will be able to get new ones without these limits

  • Can build your own

    • Uses Java

    • instructions on web page

  • RGB Recolor

  • Inverter

  • File opener: multiple files

  • AVI writer


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