Jackkyriacou's Weblog

pixels

jackkyriacou — Tue, 18 Dec 2007 17:01:55 +0000

pixels

pixel is a word short for picture elements, the small dots make up the image on the computer. whether it on a flat screen or a tube monitor. The screen is made up into a matrix of millions of pixels, you won’t be able to see the pixels individually because they are so small. this is very good because i like to look at a smooth, clear screen rather than a pixelated screen which would look like this,

if you were to set your monitor screen to 640×480 then you might be able to see individual pixels. 640×480 is a matrix of 640 to480 pixels this is alot of little dots.

one pixel can only be one colour at a time but because they are so small they blend together to to creat the image. the number of colours pixels can contain is determanied on the number bits it has got. when an image has got 256 colours you might get graniness or spotted colurs when on blends to another, but at 16, 24 and 32-bit the colour will blend smothly and there will be no graniness to the image.

image modes

jackkyriacou — Mon, 17 Dec 2007 13:10:07 +0000

RGB stand for red, green and blue and CMYK stands for cyan, magenta, yellow and black. you also have YUV which stands for luminance and chrominance and HSV which stands for hue, saturation, value.

all of theses modes are used in photoshop for general print, web publishing and you also get other modes like bitmap and indexed colour which are used for specific design work. all of the photoshop modes will allow you to edit images in 8-bitor even 16-bit which is more advanced but you can’t edit bitmap and indexed colour. if you are editing in 16-bit depth colour you might not be able to see the detail actually on screen and 16-bit has more colour detail as well.

RGB

this image shows the adobe colour space and the location of perimeters

RGB

RGB was created in 1998 by adobe system

I would say RGB is the best colour mode to work with because colour data is directly put into your RGB-based display. RGB can support a large range of colour gamunt which will be less destructive in terms of image detail while your are editing then a narrow gamut mode.RGB is the better mode because of the design workflow. if CMKY is applied to an RGB colour image rather then mixing it with CMKY will use RGB approximations. RGB is able to store a wide range value then sRGB which is the alternative to RGB.

CMYK

CMKY can be referred as process colour or four colour it is used in photoshop for masking certain colours on white backgrounds. pixals in CMKY are given a percentage for the ink primaries: cyan, magenta, yellow and black, they are basic colours used for printing colour images. if colour don’t in with the range of the CMKY colour scheme then they will be clipped to the edge of the gamut which is near the edge.

CMKY is different to RGB becasue RGB is for creating images on screen, CMKY are subtractive which is when a colour gets darker when you bend them together.

Further changes for graphic and the web

jackkyriacou — Tue, 04 Dec 2007 23:44:44 +0000

You will find that most graphics on the web our bitmap images. You store bitmap images in files like jpeg and giff. Now vector images are stored in svc graphics which stands for Scalable Vector Graphics, SVG graphic can be compressed using a program such as gzip. Gzip is a software application used to compress images

jpegs, gifs, pngs, tiffs and mpegs

jackkyriacou — Thu, 29 Nov 2007 14:36:38 +0000

Jpeg which stands for joint photographic expert group,

The JPEG committee has created many standards since it was created in 1986.  ISO had actually started to work on this 3 years earlier, in April 1983, in an attempt to find methods to add photo quality graphics to the text terminals of the time, but the ‘Joint’ that the ‘J’ in JPEG stands for refers to the merger of several groupings in an attempt to share and develop their experience.

Digital come in a Varity of file formats, most pictures on are computer use the common jpeg format. If you have a picture stored in another file format such as tiff or bitmap, you can make a copy of it in jpeg. It’s also possible to show a copy of a jpeg picture in a different format. If you have a jpeg picture an you wanted to have it in a format with out losing it quality you would put it in a tiff file format, which like a jpeg it does not lose its visual quality.A jpeg picture has the advantage of retaining high visual quality and having a relatively small file size. For the best visual quality you should show a jpeg picture with high visual quality setting.

Tiff which stands for tagged image file format,

Tiff is one of the most popualr raster file formats, Tiff was developed by Aldus and Microsoft, Aldus is now merged with Adobe systems and Adobe now holds the copyright terms to the Tiff.

A tiff image has a better colour quailty the a jpeg as you can see the difference betwwen the two forest images. The Jpeg image looks pale and duler then the Tiff image which looks brighter.



you can also see the differnce here between the two images, the Tiff is on the left and the Jpeg is on the right.

MPEG which stands for Moving Picture Experts Group,

MPEG works with the International Organization for Standardization which develops standards for digital audio and video compression and also works to develop audio and video compression files.MPEG is also a type of multimedia file,  which is denoted by the file extension mpg or mpeg. these are files that will be able to contain both audio and video. MPEG will contain the olrginal of an uncompressd movie, this will be why movie clips and music video on the internet are in the MPEG format. The major advantage of MPEG compared to other video and audio coding formats is that MPEG files are much smaller for the same quality. This is because MPEG uses very sophisticated compression techniques.

GIF/ graphic interchange format

GIF is a compressed image file format, the images use a compression formula originally developed by CompuServe. Gifs are based on index colours, its like a palette which has 256 colours. the images can quickly be transmitted on the internet  is probably the most common graphics interchange format on the Internet, this is why you see them on web pages. they work well animatied images however they lack colour range for high quailty images. I think that it was the best for me because I can compress my images using the LZW which stands for Lempel-Ziv Welch, this is a universal loss data compressor it was created by Abraham Lempel and was published by terry Welch in 1989.



png

this stands for portable network graphics which was developed in 1995

this is a png image with an 8-bit transparensy

the PNG was the alternative to the GIF, like a PNG they are lossless which is when the images are commpressed they don’t lose no detail. they can surrport up to 48-bit colour and 16-bit greyscale. PNG can compress 5% to 25% to GIF files, but PNG dont support animation like GIF do. there is a new file format in process which is like the PNG and it supports animation it is a MNG.

Bitmap images and vector images

jackkyriacou — Thu, 29 Nov 2007 14:14:20 +0000

Bitmap images

bitmap are always being composed onto your computer, a bitmap is made up of a map of dots. common bitmap filetypes include bmp which is the raw bitmap format.

Bitmap files are limited to the resolution when they are created. If you want a good print quality then will need it to be hi-resolution file, this mean you have to have a large file. If you use a low-resolution file the picture will come out fuzzy and not clear, the image will look normal on screen though. If you’re using a colour printer the designed will be for CMYK colour.

Vector images

You can see vector images are better than bitmap when you are magnifying an image. Vector makes more compact files then bitmap, this means there quicker to open and download.

You can see the difference between the pictures, the picture on the left is a real photo and the picture on the right is edited by vector illustrations. You can tell by the graphic effect on the vector picture.

vector images have small file sizes, you can stretch a vector image and it want lose it’s quality, vector images are made up by numbers and shapes, vector images are used for billboard an other large pictures

what’s the difference between a vector and a raster image

We see computer images all the time, but we rarely stop to think about the composition of those images. How are they put together? The vast majority of computer graphics fall into two categories: vector and bitmap.

a vector is more complicated and time-consuming to create than a bitmap, but both are in wide use. A vector has no pixels but a bitmap does that’s why the vector image looks clear. image file formats are for compressing images so they can be stored into a something like jpeg or mpeg the difference between the to is that mpeg is used for moving images and jpeg is for still images.

unlike bitmaps images a vector graphics is not made up of a grid of pixels but are compressed of vectors which have a start and end point. vector based images are not made up of a specif number of dots, they can be scaled to a larger file size and the image quailty want be losted.

graphic file formats

jackkyriacou — Thu, 29 Nov 2007 13:45:14 +0000

There are many varieties of graphics and images. Most are dependent upon a particular hardware and operating system plat forms. JPG, TIFF, BMP, GIF and Png these are bitmap images, they are the best images used for screen play.