Digital Photography

BITMAP GRAPHIC ESSENTIALSBITMAP GRAPHIC ESSENTIALS

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ContentsContents1.Describe a bitmap based graphic.

2.Use a graphics application software g p pppackage to edit bitmap based graphic.graphic.

3 Create and print a bitmap based3.Create and print a bitmap based graphic.

4.Insert stored graphics into a current d i d i t i l d t

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drawing and into a simple document.

Describe a bitmap based graphicDescribe a bitmap based graphic.

• Identify the features of a bitmap based graphic.g p

• Describe how each graphic type is stored, ie file formatie file format

• Identify examples of bitmap based graphics.

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Identify the features of a bitmap based graphic.

• Raster Graphics = Bitmap based graphicsRaster Graphics Bitmap based graphics– Graphics made up of rows and columns of pixels.

• PixelsTh ll t it f t hi A i l– The smallest unit of a raster graphic. A pixel contains an individual colour.

• Colour depth– The number of possible colours that can be

contained in a raster graphic. Eg 24 bit colour which gives 16.7 Million different colours.

R l ti• Resolution– A measure of the quality of the image in terms of

how many pixels it has. Eg 800x600 pixels or 300 i l i h( i)300pixels per inch(ppi)

• Digital data– Data that can be expressed in terms of numbers. It

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pis both accurate and reproducible.

What are these file types?What are these file types?jpg BMP.jpg .BMP

.GIF

.PSD.xls.doc

rtf

.xls

.rtf.TIF .PDF

.txt

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.ppt

Lets sort them out ?Lets sort them out.?Raster Graphics Documents

.txtRaster Graphics Documents

.jpg .rtf.BMP

xls .doc.PSD .PDF.GIF

.xls

.TIF .ppt

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ResolutionResolutionImages can be

measured in 3 ways.• Megapixels eg 7.1MPg p g• The number of pixels

Width x heightWidth x height.Eg 800x600=480,000pix800x600 480,000pixels or 0.5MP

Th b f i l i h f i i•The number of pixels per inch for printing on paper.Common resolutions include:

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•72 pixels per inch (ppi) for screen quality.•150 pixels per inch (ppi) for Newspaper quality.•300 pixels per inch (ppi) for photo quality.

Colour DepthColour DepthThe number of possible colours that can becolours that can be contained in a raster graphic. g p

Colour is stored in photographs by allocating storage space in the form of bits and bytes of data Each 24 bit colour means 24 bitsbits and bytes of data. Each pixel in a raster graphic is allocated a colour.

24 bit colour means 24 bits or 3 bytes of data is allocated to each pixel in the image.allocated a colour.

Eg 24 bit colour gives 16.7 Million different colours.

to each pixel in the image.

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Colour DepthColour DepthColour No of Bits Bytes Notesdepth ColoursBlack and 2 colours 1bit 1/8 Commonly used for scanned text

documentsWhite 2 to the power of 1 (because there is only 1 bit of data/pi el)

byte documents

bit of data/pixel)

Greyscale 256 versions

8 bits

1 byte Greyscale is commonly referred to in photography as black and

hit b t b i l th iversions of grey2 to the

bits white but obviously the image contains more than just pure black and pure white.

power of 8

24bit C l

16.7Million l

24 bit

3 bytes Red – 1 byte – 256 variationsGreen – 1 byte – 256 variations

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Colour colours2 to the power of 24

bits Green – 1 byte – 256 variationsBlue – 1 byte – 256 variations256x256x256=16.7Million

Calculating File SizesCalculating File Sizes.File sizes for uncompressed raster graphics can be p g p

calculated by multiplying the number of pixels by the number of bits per pixel. p p

Example1: Calculate the following file size as a bitmap.

Example2: Calculate the following file size as a bitmap.

A greyscale image is 800 x 600 pixels800 x 600 = 480,000 pixelsa greyscale image uses 1 byte of data

i l

A 24bit colour image is 800 x 600 pixels800 x 600 = 480,000 pixelsa 24bit colour image uses 3 bytes of d t i lper pixel.

800 x 600 x 1 = 480,000 bytes divide by 1024 to get Kilobytes 800 x 600 x 1 /1024 = 469 Kb

data per pixel. 800 x 600 x 3 = 1,440,000 bytes divide by 1024 to get Kilobytes 800 x 600 x 3 /1024 = 1406Kb800 x 600 x 1 /1024 = 469 Kb 800 x 600 x 3 /1024 = 1406Kb

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File FormatsFile FormatsGraphics are stored in files Common File types include:Graphics are stored in files. Common File types include:• BMP an uncompressed raster graphic filetype. This is Microsoft's

native graphic file format.• JPG or JPEG a lossy compressed raster graphic JPEG supports• JPG or JPEG a lossy compressed raster graphic. JPEG supports

millions of colours and allows for graphic compression. • GIF a lossless raster graphic that can only show 256 colours. Often

used for logos and animated graphics on web pagesused for logos and animated graphics on web pages.• TIF a lossless compressed raster graphic. Can store layers and

multiple pages.• PSD This is Photoshop's native file format If you have created aPSD This is Photoshop s native file format. If you have created a

graphic with a multitude of layers (especially type layers), and you want to save these layers for any changes that you intend to make in the future, then save the graphic in Photoshop format because it i th l f t th t ll t l F ll this the only format that allows you to save layers. For all other formats, you must first Flatten Layers (under the Layer menu) before you can save the graphic.

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RAW (* raw)RAW ( .raw)

• Professional Digital Cameras (High End)

• Uncompressed and unedited – excellent quality and detailq y

• Requires dedicated software to view qimages

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TIFF (* tif)TIFF ( .tif)

• Tagged image File Format• A lossless compressed raster graphicA lossless compressed raster graphic• Supports Layers and Multiple pages• Commonly used for scanned text

documentsdocu e ts• A common file type used in desktop

p blishingpublishing

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JPEG (* jpg)JPEG ( .jpg)J i t Ph t hi E t G• Joint Photographics Expert Group

• Most Common Image File used by DigitalMost Common Image File used by Digital Cameras

• “Lossy” Compression – loses data on compression by merging colours.

• Image quality degrades as compression is increasedincreased

• 16.7 million colours

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GIF (* gif)GIF ( .gif)G hi I t h F t• Graphics Interchange Format

• Lossless compressed raster graphic

• Allows for a colour range of 2 to 256 Colours

• Not enough colour depth for photos but can have transparent sections

• Used for text, logos, animations and simple pictures.

• Commonly used for the Web although the PNG file typeCommonly used for the Web although the PNG file type may partially replace it.

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Photoshop Document (* psd)Photoshop Document ( .psd)

• Native Adobe Photoshop file format

• Allows complex image including layers and filter effects to be saved and edited at a later date

• Large file size

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PDF (* pdf)PDF ( .pdf)• Portable Document Format.• A file type developed by Adobe to standardise document• A file type developed by Adobe to standardise document

display.• Can contain images and text. Images are compressed

ithi PDF fil ith GIF JPG T t i t d ithwithin PDF files as either GIF or JPG. Text is stored with its fonts embedded.

• Pages will be displayed exactly as they were formattedPages will be displayed exactly as they were formatted on the designers computer.

• Commonly used in web sites and can contain multiple pages popup notes and hyperlinkspages, popup notes and hyperlinks.

• The Adobe Reader software is Free to download from the web.

• Documents can be password secured to stop changes or even printing.

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Raster Graphic File Types Comparison

Fil T C i W b L M lti l M i PFile Type Compression Web Layers Multiple Pages

Main Purpose

RAW No NO NO NO High grade images direct from camera.

TIFF Lossless (Large file sizes)

Yes Yes Yes Scanned text documents

JPG Lossy (Small file sizes)

Yes No No Photos on the Web or to email.

GIF Lossless Yes No No Animations and logos on the web or logosGIF Lossless (Small file sizes)

Yes No No Animations and logos on the web or logos and simple graphics in documents. Can have transparent sections. Limited up to 256 colours

PSD NO No Yes Used by Photoshop for works in progress

PDF Yes(Variable)

Yes No Yes Displaying documents exactly as they were designed containing text fonts and

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(Variable) designed containing text, fonts and graphics

Identify examples of bitmap based graphics.

Ch k th ti• Check the properties of some common file typestypes.

• Zoom into the image and see the pixelsand see the pixels.

• Check the File properties fromproperties from Windows Explorer. Right Click on the fileRight Click on the file and choose properties.

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p p

Editing raster graphicsEditing raster graphics.

• Open a graphics applications software package and identify the basic information displayed on the screen, eg Photoshop or Paintshop.

• Identify the purpose of each of the basic graphics tools.U hi t l t dit hi i h• Use graphics tools to edit a graphic, eg resize, change shape, colour.

• Save a graphic differentiating between 'save' and 'saveSave a graphic, differentiating between save and save as'.

• Store the graphic in a specified folder.• Exit the application without loss of data.

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Model makeoverModel makeover

• Open the file for the model makeover.

• Identify the parts of the screen.• Select pixelsSelect pixels• Change colours

Save changes to local C: drives• Save changes to local C: drives.

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Stonehenge SunsetStonehenge Sunset

• Use layers to create the Stonehenge sunset from 3 images.

• The selection and magic wand gtools can be used to delete unwanted parts of the layers.p y

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Create and print a bitmap based graphic.

• Create a graphic using graphic tools to draw boxes, circles, text, lines etc.U th f t f th hi ft• Use the features of the graphics software application to enhance the drawing, eg morphing artistic appearance colour balancemorphing, artistic appearance, colour balance, etc.

• Print the graphic using the functions of the e g ap c us g e u c o s o egraphics software application.

Do the Drawing with Photoshop Exercise.

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Inserting stored graphics into documents.

• Retrieve created graphic from storage and insert into a current drawinginsert into a current drawing.

• Insert a graphic into a simple created document.

• Edit the graphic from the documentEdit the graphic from the document.• Print the document.

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