| | Imaging 1 | ||
 | Exercise 7 – Selections | ||
| Name | | ||
| | § This is a formative assessment instrument § You must be rated ‘Competent’ in this assessment item. | ||
| Learning Outcomes | Learning Outcome 5 - Identify and explain a range of digital imaging concepts such as colour mode, colour space and bit depth as well as demonstrate typical fundamental digital image enhancement techniques. Learning Outcome 6 - Identify digital image workflow patterns and create a simple file management methodology that conforms to established industry norms. | ||
| Tasks | 1) Copy the ‘Lesson 8 ’ folder from the server and place it on the desktop. (Remember to delete this folder when you have completed this exercise). 2) Start Photoshop CS4 and open the document ‘Selections.jpg’ 3) Display the Histogram palette (‘Windows -> Histogram’) 4) Open the levels or curves palette (‘Image -> Adjustments ->Levels . . .’ and adjust the tonal range of the entire image, then close the palette. 5) Select the rectangular Marquee tool – set the feather value to 0, and the style to ‘Normal’. a) Select a small rectangular portion of the image and observe the histogram. b) Select a different area of the image and observe the histogram. c) Click within the selected area and drag it to a new location. d) What is the histogram doing ? e) Open the levels or curves palette and make a change. What happens ? f) Use the selection types buttons to add to and remove areas from the selection  .g) Use the Shift and Alt keys to add to and remove areas from the selection. h) Press  +D or click once in the image to discard the selection.i) Use the History palette to undo all the changes you have made. j) Set the style to fixed ratio, enter a value for width and height (eg 2 and 3), then select an area of the image. k) Set the style to fixed size, enter a value for width and height (eg 200 and 100), then select an area of the image l) Set the feather value to 25, select an area of the image and make a tonal or colour change to the image. What do you observe ? m) Press  +D or click once in the image to discard the selection.n) Use the History palette to undo all the changes you have made. 6) Select the circular Marquee tool – set the feather value to 0, and the style to ‘Normal’. a) Select a small portion of the image. b) Press  +D or click once in the image to discard the selection.c) Press and hold the shift key while you select a portion of the image. What happens ? d) Press and hold the shift key while you select another portion of the image. What happens ? 7) Select the Lassoo tool. a) Select a small portion of the image. b) Add and subtract areas to the selection and use the feather option. c) Discard the selection 8) Select the Polygonal Lassoo tool. a) Select part of the image by clicking a start point and adding nodes until you click on the start point to finalise the selection. b) Start a new selection and use the Esc key to abort the selection before you finalise it. c) Start a new selection, add some nodes and then use the Delete key to backstep through the nodes you have added. d) Set the feather value to 2. e) Select the two areas of the timber wall. f) Use the Hue control to change the colour of the wall. g) Go to ‘Select->Save Selection . . .’ and save the selection as Walls. h) Discard the selection. 9) Select the Magnetic Lassoo tool. a) Select the grey metal roof by clicking a start point and adding nodes until you return to the start point to finalise the selection. Use the Esc key to abort, and the Delete key to remove unwanted nodes if you need to. Click on any point to force a node to be created. You may need to use the other selection tools to tidy up edges etc to make an accurate selection. b) Save the selection as Roof. 10) Select the Magic Wand tool. a) Set the tolerance to 32 b) Click in the sky to select part of the sky. c) Hold down the shift key and click to add all the sky and clouds into the selection. Use  +Z to undo the last addition if required.d) Save the selection as Sky 11) Use whichever tools you want to make and save a selection for the bricks. 12) Select ‘Select->Load Selection . . .’ and set Operation to ‘New Selection’ to reload the selection of the sky. a) Use ‘Select->Inverse’ to invert the selection ie the entire building will be selected instead of the sky. b) Save this selection as ‘Building’ 13) Choose ‘Select->Color Range . . .’ a) Click on the blue part of the sky and use the Fuzziness slider to select all the blue sky. b) Use the Burn tool to darken just the lower part of the blue sky without affecting the building or the white clouds. c) You can use  +H to hide the selection outline while you do this. Use  +H to reveal the selection outline when you have finished.14) Close the document. 15) Quit Photoshop. 16) Delete the ‘Lesson 8’ folder from the desktop. 17) Shutdown the computer. | ||
| | |
Sunday, May 16, 2010
EXERCISE 7
EXERCISE 5
Imaging 1 | |||
| Exercise 5 – File Types & Sizes | ||
Names | |||
§ This is a formative assessment instrument § You must be rated ‘Competent’ in this assessment item. | |||
Learning Outcomes | Learning Outcome 1 - Identify and define a range of file types and describe their uses. | ||
Tasks | 1) Copy the ‘Lesson 6’ folder from the server. 2) Open the file ‘Img 1 – Ex 5 – Image.tif’ in Photoshop and do the following :- Select ‘Image -> Image Size …’ :- |
1. Width of the image in pixels | |
2. Height of the image in pixels | |
3. Calculate the size of the image in Megapixels | |
4. What is the specified resolution of the image | |
5. Width of the image in cm | |
6. Height of the image in cm |
Select ‘File -> Save As…’ and save the image in the following formats. Name the files to clearly identify them.
After each save close the image and reopen to save to the next format. Use the Finder/File Browser to record the sizes of the files created.
1) The original .tif file | |
2) TIF file using LZW compression | |
3) Photoshop .psd file | |
4) Jpeg file – Quality level 12 | |
5) Jpeg file – Quality level 10 | |
6) Jpeg file – Quality level 5 | |
7) Jpeg file – Quality level 1 | |
8) GIF file – 256 colours – no dithering | |
9) GIF file – 256 colours – diffusion dither | |
10) GIF file – 16 colours – diffusion dither |
Select ‘Image -> Mode -> Greyscale’ to convert the image to a grayscale image & save as
11) TIF file (no compression) |
Select ‘Image -> Mode -> Bitmap’ to convert the image to a bitmap image & save as
12) TIF file (no compression) |
| | |
| |
Common Graphic File Formats
| | Imaging 1 | ||
| Common Graphic File Formats | ||
| Preamble | This document gives a basic introduction to various file types for saving digital images. |
| Background | During the early years of computer graphics development and the race for dominance by both hardware and software manufacturers, many proprietary formats were designed. Every graphics program saved files in its proprietary—or native—format, and therefore, any file saved from a specific application and used exclusively by that application was—and still is—known as a native file. Unfortunately, these native files weren’t always readable by other applications ... especially when the native file was originated in a Mac-based application and the target application was PC-based or vice versa. With greater demands for inter-application compatibility and cross-platform compatibility, many developers and manufacturers realized that survival was closely linked to meeting those demands. Today, most major graphics applications can save and open both in their native formats and in a number of other formats that can be used to transfer images from one application to another or from one platform to another. |
| TIFF File (.tif) | TIFF—or Tag Image File Format—was developed by Aldus Corporation in 1986, specifically for saving images from scanners, frame grabbers, and paint/photo-retouching programs. Today, it is probably the most versatile, reliable, and widely supported bit-mapped format. It is capable of describing bilevel, grayscale, palette-color, and full-color image data in several color spaces. It includes a number of compression schemes and is not tied to specific scanners, printers, or computer display hardware. The TIFF format does have several variations, however, which means that occasionally an application may have trouble opening a TIFF file created by another application or on a different platform. |
| PICT File | The PICT format—which is not an acronym—is native to the Macintosh. It first appeared in 1984 with the introduction of MacDraw software. Since then, it has been used by many applications, especially when images are designed for screen previews. It is great for presentations, screen displays, and video work. The PICT format can contain both bit-mapped and object-oriented graphics. It is a standard format for graphics that are cut or copied to the Clipboard and for drawings that will be output on raster printers. |
| BMP file (.bmp) | BMP is the standard Windows bitmap image format on DOS and Windows-compatible computers. When saving an image in this format, you can specify either Microsoft Windows or OS/2 format and a 1-bit to 24-bit depth for the image. For 4-bit and 8-bit images, you can also choose to use Run-Length-Encoding (RLE) compression; this compression scheme is lossless, that is, it does not discard detail from the image. |
| EPS File (.eps) | EPS—or Encapsulated PostScript—files are the standard format for storing high-resolution PostScript illustrations. The EPS format—which was introduced in the mid-’80s allows both Mac and Windows users to save bit-mapped screen representations of screen images. These previews, however, don’t travel well across platforms. An EPS file generally has two parts: a PostScript (text) description that tells a PostScript printer how to output the resolution-independent image, and (optionally) a bit-mapped PICT or TIF image for on-screen previews. A drawing saved in EPS format can be imported into other documents and scaled and cropped, but its contents are often no longer editable, even by the program that created it (Adobe Illustrator files are the exception). |
| GIF File (.gif) | GIF—or Graphics Interchange Format—files define a protocol intended for the on-line transmission and interchange of raster graphic data in a way that is independent of the hardware used in their creation or display. The GIF format was developed in 1987 by CompuServe— one of the world’s most successful bulletin board services—for compressing eight-bit images that could be telecommunicated through their service and exchanged among users. The GIF file is defined in terms of blocks and sub-blocks which contain relevant parameters and data used in the reproduction of a graphic. A GIF data stream is a sequence of protocol blocks and sub-blocks representing a collection of graphics. |
| JPEG File (.jpg) | JPEG is a standardized image compression mechanism. The name derives from the Joint Photographic Experts Group, the original name of the committee that wrote the standard. In reality, JPEG is not a file format, but rather a method of data encoding used to reduce the size of a data file. It is most commonly used within file formats such as JFIF and TIFF. JPEG File Interchange Format (JFIF) is a minimal file format which enables JPEG bitstreams to be exchanged between a wide variety of platforms and applications. This minimal format does not include any of the advanced features found in the TIFF JPEG specification or any application specific file format. JPEG is designed for compressing either full-color or grayscale images of natural, real-world scenes. It works well on photographs, naturalistic artwork, and similar material, but not so well on lettering or simple line art. It is also commonly used for on-line display/transmission; such as on web sites. A 24-bit image saved in JPEG format can be reduced to about one-twentieth of its original size. Because it discards data, the JPEG compression scheme is referred to as lossy. This means that once an image has been compressed and then decompressed, it will not be identical to the original image. A higher level of compression results in lower image quality, while a lower level of compression results in better image quality. In most cases, compressing an image using the Maximum quality option produces a result that is indistinguishable from the original. When saving in JPEG format, you can specify an image quality and compression level for the file. To specify image quality, enter a value between 0 and 10 or choose an option for Quality; to specify the amount of compression, drag the slider. A trade-off exists between the image quality and the amount of compression; an image compressed using Maximum quality is less compressed (and thus takes up more disk space) than an image compressed using the Low quality option. In addition, you can select a format option for the JPEG file. To optimize the color quality of the image, select Baseline Optimized. To save the file as a progressive JPEG, select Progressive. This option displays the image gradually as it is downloaded from a Web browser, using a series of scans to show increasingly detailed versions of the entire image until all of the data has finished downloading. However, progressive JPEG images require more RAM for viewing and are not supported by all Web browsers. When you select Progressive, you can also specify the number of progressive scans. |
| JPEG 2000(.jp2) | JPEG 2000 is a wavelet-based image compression standard. It was created by the Joint Photographic Experts Group committee in the year 2000 with the intention of superseding their original discrete cosine transform-based JPEG standard (created 1992). The standardized filename extension is .jp2 for ISO/IEC 15444-1 conforming files and .jpx for the extended part-2 specifications, published as ISO/IEC 15444-2, while the MIME type is image/jp2. |
| PNG File (.png) | The PNG format was developed as an alternative to the GIF format and, like GIF, is used for displaying images on the World Wide Web and other online services. PNG preserves all color information and alpha channels in an image and uses lossless compression to reduce file size. When saving an image in PNG format, you can choose to display the image in gradually increasing detail as it is downloaded. To do this, select Adam7 for Interlace. You can also select a filtering algorithm, which is used to prepare the image data for compression. |
| PDF | The PDF format is used by Adobe Acrobat, Adobe’s electronic publishing software for Macintosh, Windows, UNIX, and DOS. You can view PDF files using the Acrobat Reader software included on your Adobe Photoshop CD-ROM. Based on the PostScript Level 2 language, PDF can represent both vector and bitmap graphics. For the purposes of representing pages, PDF pages are identical to PostScript pages, but PDF files can also contain electronic document search and navigation features. PDF files, for example, can contain hypertext links and an electronic table of contents For more information on PDF and Adobe Acrobat see the Electronic Publishing Guide included on the Adobe Photoshop Tutorial CD-ROM. |
| Photoshop File (.psd) | A Photoshop file is the native file format for Adobe Photoshop. A file saved in this manner can only be opened and edited in Photoshop. However, the user has the option to save the file in a variety of other formats that are readable in both the Macintosh and PC environment. The major advantage of the Photoshop format becomes apparent when working on documents with layers. For example, a background can be created on one layer, then graphics can be added on a second layer, a drop-shadow on a third layer and text on yet another layer. Each layer is independent of the others and can be edited separately without affecting the contents of the other layers. Photoshop supports the preservation of layer information, so that the layers can be preserved for additional editing. |
Sunday, May 2, 2010
HISTOGRAMS
Histogram is a graph. In our image file with pixels that have a Red Green and a Blue value.... that value will lie between 0 - 255.
When we combine the values ie:
R 64
B 125
G 202
It gives a lightness/ brightness value for each pixel.
0 is Black
233 is White.
Something about Tonal Range...
Histogram is really important in analyzing your image.
Gaps are bad because it means that you are missing tones.
There will be peaks and troffs. It depends on the scene you are trying to capture.
When we combine the values ie:
R 64
B 125
G 202
It gives a lightness/ brightness value for each pixel.
0 is Black
233 is White.
Something about Tonal Range...
Histogram is really important in analyzing your image.
Gaps are bad because it means that you are missing tones.
There will be peaks and troffs. It depends on the scene you are trying to capture.
Study Guide
File extention: used to indicate what is inside the file. (you can't change a file by just changing the extention. This is an important distinction)
example of file extentions. .jpg, .tif, .psd, .png, .exe, .pdf *jpeg2000 - uses a different type of algorithm to compress data, has the option of having loss-less compression. Has not become popular.
Image size: how do you express the size of an image? MB, resolution, dpi, blah blah blah.. all of them are acceptable ways of expressing the size.
Resolution: pixels per inch AND pixels per centimetre. The convention however is to use pixels/inch.
divide by 2.5 to get centimetres.
Bit: Binary Digit... can only be 2 numbers: 1 or 0
8 bits to 1 BYTE.
Can be represented in 2^8 ways.
Photographic Images - Raster
Lines and Shapes - Vector
Vector images can maintain all information.
Raster images deteriorate the more
****Bit Depth: look up bit depth
Three subtractive primary colours: Cyan Magenta Yellow used for printing
Three additive primary colours: RBG used for monitors that things that emit light.
Complimentary Colours: different sides of a colour wheel are complimentary colours.
In order to compress an image file you must sacrifice information (FALSE!) Tif, Raw, Png, etc.... can all save information.
What results from adding Red and Green (use colour wheel)... R+G = Y
****Bit Map: can only be black or white therefore the bit depth is 1.
Duo tone image: image that is made by using two different colour printing inks. (Andy Warhol Style)
Index Image: each pixel is allocated a number and you look at the look up tables to find out what the number is. Used for graphic images like Icons or Logos.
Dithering: mingling the colours together to create new tones.
Rasterising: Taking a vector image and convert it to pixels as opposed to lines. There ARE some programs that can turn a raster image into a vector image... but it's a pointless venture really.
IMAGE SIZE and RESOLUTION CALCULATIONS:
2000 x 2500 pixels
= 5 000 000 pixels
= 5 MP (Megapixels)
Image Size in Inches:
2000 x 2500 with a resolution of 250dpi
2500:250 = 10inches
2000:250 = 8 inches
There you go, basic BASIC equations.... god damn..
****What resolution would require an image size of 12inch by 2.5 inches.?
****Which files are loss-less compression?
If you resize and image from 150 to 250dpi, what happens??? If you go in and start changing the size of the image, you want to know if you are destroying the image. Resize without resampling, which means the resolution is changing which means that there are a number of pixels lost.
Q21 = A
Q22 = B
Yellow and Magenta Inks combine to make RED!!
THE END!
example of file extentions. .jpg, .tif, .psd, .png, .exe, .pdf *jpeg2000 - uses a different type of algorithm to compress data, has the option of having loss-less compression. Has not become popular.
Image size: how do you express the size of an image? MB, resolution, dpi, blah blah blah.. all of them are acceptable ways of expressing the size.
Resolution: pixels per inch AND pixels per centimetre. The convention however is to use pixels/inch.
divide by 2.5 to get centimetres.
Bit: Binary Digit... can only be 2 numbers: 1 or 0
8 bits to 1 BYTE.
Can be represented in 2^8 ways.
Photographic Images - Raster
Lines and Shapes - Vector
Vector images can maintain all information.
Raster images deteriorate the more
****Bit Depth: look up bit depth
Three subtractive primary colours: Cyan Magenta Yellow used for printing
Three additive primary colours: RBG used for monitors that things that emit light.
Complimentary Colours: different sides of a colour wheel are complimentary colours.
In order to compress an image file you must sacrifice information (FALSE!) Tif, Raw, Png, etc.... can all save information.
What results from adding Red and Green (use colour wheel)... R+G = Y
****Bit Map: can only be black or white therefore the bit depth is 1.
Duo tone image: image that is made by using two different colour printing inks. (Andy Warhol Style)
Index Image: each pixel is allocated a number and you look at the look up tables to find out what the number is. Used for graphic images like Icons or Logos.
Dithering: mingling the colours together to create new tones.
Rasterising: Taking a vector image and convert it to pixels as opposed to lines. There ARE some programs that can turn a raster image into a vector image... but it's a pointless venture really.
IMAGE SIZE and RESOLUTION CALCULATIONS:
2000 x 2500 pixels
= 5 000 000 pixels
= 5 MP (Megapixels)
Image Size in Inches:
2000 x 2500 with a resolution of 250dpi
2500:250 = 10inches
2000:250 = 8 inches
There you go, basic BASIC equations.... god damn..
****What resolution would require an image size of 12inch by 2.5 inches.?
****Which files are loss-less compression?
If you resize and image from 150 to 250dpi, what happens??? If you go in and start changing the size of the image, you want to know if you are destroying the image. Resize without resampling, which means the resolution is changing which means that there are a number of pixels lost.
Q21 = A
Q22 = B
Yellow and Magenta Inks combine to make RED!!
THE END!
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