Skip to Main Content


Jessie Ball duPont Library

Image Resources

Image Information

Downloading and Storing Images

April  13, 2012

 

Types of Images

 

JPEG- (Joint Photographic Experts Group)   Best for photographs or pictures with lots of color detail.  JPEGs can be up to 16 million colors. 

Tiffs-(Tagged Image File Format.  It is a file format for graphics for the Mac and the PC. Tiff images are typically smaller because of the high compression rate.  ITW uses Tiffs for Archival copies which we make derivatives of our images for our image database.

Camera Raw Images—A camera raw image file contains minimally processed data from the image sensor of either a digital camera, image scanner, or motion picture film scanner.  It is a form of a negative film image.

PNG-8 (Portable Networks Graphic)  Best for clipart and graphics with few colors, or large blocks of color GIFS (Graphics Interchange Format)  Best for text, clip art and line drawings, and other graphics. 

PNG-24  Best for photographs or lots of colors or pictures with lots of color detail.

BMP (Bitmaps )  Typical format for computer icons and images.  Large in file size, but has high quality.  Does not scale well.

 

What Does Pixel Dimensions Mean?

Pixel dimensions are the number of pixels making up the width and height of an image (e.g., 300 X 300)

 

What Does Resolution Mean?

Resolution is the detail of an image and is measured in pixels per inch (ppi).  Generally, an image with a higher resolution produces a printed image with higher quality.

The following is a good guide for sizing an image that is longer than it is tall.

Format

Dimensions

Ppi

File Size

Web thumbnail

150X100

72 ppi

44-70k

Web Image

360-X216

72-96 ppi

230k-405k

3X5 print

1000X600

200 ppi

1.72MB

Desktop Wallpaper

 

1024X768

 

72 ppi

 

2.3MB

 

 

 

What does these file sizes mean?

 

Bit—A bit is a binary digit

Byte—A byte is 8 bits

Kilobyte (KB) is 1,000 bytes

Megabyte—A megabyte (MB) is 1,000,000 bytes.

How Do I Store My Images?

  1. CDs or DVDs (make sure you have a copy of the original) 

  2. Portable Hard drives (be able to access it in case of emergency)

  3. Servers (if you have access to one)

  4. Paid services that backup your files

  5. Free websites i.e, Flickr, Photobucket, Google's Picasa etc.

  6. Folders/files on your computer

  7. Memory sticks or Jump Drives

  8. iCloud Services

  9. iPhoto

Organizing my Images

Lightroom

Picasa

iPhoto

Folders on Your Computer

Compiling a Database using Metadata

ARTstor (faculty) limited storage

Other Information on Storage Issues