Vector and Raster Images

1. The picture is enlarged with no pixelation.
2. Because vector graphics do not work on the principle that bitmap does. Vector graphics use mathematical equations and it is only the inferiority of the monitor that induces aliasing.
3. Yes because vector works on mathematical equations this allows you to change each equation, rather than raster images which allow you to manipulate each pixel.
4. You can edit any part of the image because vector graphics work on mathematical equations this allows you to change each equation, rather than raster images which allow you to manipulate each pixel.
5. The image is behaving in this way because, vector works on mathematical equations this allows you to change each equation, rather than raster images which allow you to manipulate each pixel.

In Photoshop, when saving different types of picture as jpeg a quality selection box appears.

From here you can choose various quality settings.

From here you can choose from various quality settings. On the top side of the Image Options sector you can click on a drop-down box to choose a basic level of image compression.

In the sector below this you can use a slider which enhances the control you have over the amount of compression.

At the bottom you have format options, this allows you to choose from Baseline (“Standard”), Baseline Optimized, and Progressive Scanning, from 3-5. Baseline (“Standard”) is used because it's a format recognized by most Web browsers, Baseline Optimized however, is optimized for color and is a slightly smaller file size. Progressive displays a series of increasingly detailed scans (you can specify the amount from 3-5) as the image downloads. Baseline Optimized and Progressive JPEG images are not always supported by all Web browsers so Baseline (“Standard”) is often the format to save as if publishing on the internet.

You can change the compression settings of the JPEG file format for various reasons, mainly due to size. This size issue is down to the internet, and download speeds. The basic fact is, if you have a larger file size, then it will take longer to download. So the image is often published so it has a decent quality, (doesn't appear too pixelated or aliased) but isn't too large. For example, a JPEG saved as a medium file size, and baseline (“Standard”) would be a more acceptable size, compared to a maximum quality JPEG with 5 progressive scans, as this may take some time to download onto the computer. This is also applicable to other file formats such as .MP3 compared to .WAV

GIF Transparency

The acronym GIF stands for Graphics Interchange Format. GIF format is a lossless compression file format. It uses repetition and redundancy in the file itself to reduce the size of an image, (substitution) rather than degrading the quality. For example, if it has a simple code, it might use the first part of that code instead of reproducing that code each time, so every time it repeats it thinks of the first part of code and repeats it.

To prepare to set transparency for GIF's you need to choose a color that doesn't occur naturally so that parts of the picture that you want to be seen don't accidentally get made transparent. Cyan is a color that doesn't normally occur naturally so choosing this color, we can delete all parts of the picture with this color and make it transparent, similarly to chroma-key, but to a GIF file instead of a video file.

The numbers in the color selection box regard to the intensity of the red, green, and blue colors.

Here you can see that the red slider has been left at an intensity of 0, green set to 255 and blue set to 255 also, (maximum).

This allows you to mix the three primary colors together to make any secondary colour you prefer with just three sliders.

Aswell as choosing the threshold of the mix of colors you can also set the tolerance of the transparency. This is done by clicking on the background box under “tolerance” and choosing an amount between 1-255. The higher the tolerance, the wider band of light frequencies it will make transparent, the lower the tolerance the smaller bandwidth of colours it will choose to make transparent.

When saving the GIF select the “Save For Web & Devices” and another screen will appear. Here on the left you will be able to decide between all the colours in the image that may contain traces of the flood fill colour you used earlier, in this case, Cyan.

You can choose the color that you wish to eliminate and click the transparent button.

When enlarging a Raster graphic, the software automatically tries to smooth out the pixels so that you don't notice its resolution easily, however, by doing this it creates the pixelated effect as seen below.