Resolution

Resolution

1. Pixels, resolution and Image size Lecturer: Fran Jackson

2. Definition:  Resolution is the term used to describe the number of dots, or pixels, used to display an image. Some examples...

3. picture Fran Jackson

4. PPI =  (pixels per inch) refers to screen resolution DPI  = (dots per inch) refers to print resolution The two are interchangeable Often images are referred to as high resolution (hi-res) or low resolution (low-res). High resolution would be an image intended for print, generally having 300 dpi or more. Low resolution refers to images only intended for screen display, generally having 72 - 150 dpi.

5. Image enlarged so that you can see the individual pixels, each pixel is a solid square of colour.

6. Standard screen resolution is 72 dpi and standard print resolution is 300 dpi Circle at 72 dpi enlarged to see individual pixels

7. Standard screen resolution is 72 dpi and standard print resolution is 300 dpi Same circle at 300 dpi enlarged to see individual pixels

8. Image types

9. Raster (Bitmap) • Made of pixels; tiny dots or squares* of colour • Represents and edits photo and photo-like elements better than vector programs with the use of continuous tones. The use of different colour pixels allows for smooth blends of colours. Disadvantages • Is bound by the number of pixels in the image. It cannot be scaled up without losing quality. •Large (dimension) & detailed images equal large file size • Some service providers like engravers, stencil-cut signs, etc, must have vector art. • It is more difficult to print raster images using a limited amount of spot colors • Depending on the complexity of the image, conversion to vector may be time consuming

10. Vector • Made of mathematical calculations that form objects and lines • Can be scaled to any size without losing quality • Resolution-independent: Can be printed at any resolution • Number of colours can be easily increased or reduced to adjust printing budget. • A large dimension vector graphic can maintain a small file size. • Vector art is required by many service providers • Can be easily converted to raster Disadvantages • It is not the best format for photographs or photo-like elements with blends of colour

11. Image scaled 600% On the left the vector image is still sharp But On the left the bitmap image is blurry

12. Examples of Bitmap of Raster images

13. All jpg’s are Bitmap or Raster images, they are made from a mosaic of pixels jpg file Characteristics of a jpg file: Small file size - compressed file format, makes the original file a smaller files size due to lossy compression. Smooth gradients like are found in a typical photograph Be careful not to over compress a jpg file picture Fran Jackson

14. Too much jpg compression will distort your image jpg distortion picture Fran Jackson

15. RAW is not an acronym for anything, is simply is the raw unprocessed data from your image sensor

16. JPEG = Joint Photographic Experts Group, nowadays shortened to jpg or JPG

17. PNG = Portable Network Graphics

18. GIF = Graphics Interchange Format

19. TIFF = Tagged Image File Format

20. Examples of Vector images

21. Vector is a series of lines filled with colour, it is created by the computer. Therefore the computer is able to manipulate it’s size and properties easily and without loosing any quality or edge definition Vector graphics generally have simple outlines and solid colour fill Vector graphics are small file size also, they are not good for complex images Vector graphics are commonly used for things like logos

22. All text in Photoshop is vector Tools like the shape tool can be used in a vector mode or a bitmap mode Just make sure you choose the shape layer mode for vector You can’t mix vector and bitmap on the same layer, or use bitmap tools on a vector