WEEK 13 - Case Study on The Horrible DPI Mistake

The scenario are....- a print shop/graphics designer/magazine asks a client for a photo at 300dpi. They wish to print it out 7” x 5”. The client already has a beautiful digital photo with pixel dimensions of 2048x1536. The client notices that the photo editing software is showing that the photo is set to 72 dpi. So, following order the client types in 300 to reset the dpi to 300. In doing so the image is resample and enlarged over 4 times to pixel dimensions of 8533 x 6400. The client sends this enlarged 300dpi photo. The print shop/graphics designer/magazine rejects it (too grainy, too color blotches).The client is crushed.
The sad thing is that the client already had the perfect photo (2048 x 1536 @ 72dpi) which would have been beautifully printed at 7” X 5” (at 292.6 ppi). The print shop/graphics designer/magazine didn’t know what they really want..

DPI is PPI... its just the same... However, terms DPI is dot per inch for viewing from PC screen, and PPI is dot per inch for printed view.

Foto A dgn 72dpi akn nmpk jelas utk screen viewer je, and bkn pd printed.. Foto 72dpi kalau kita print akn menjadi tidak jelas..... Tapi kalau kita increase kn dpi dia br la foto tu akn lebih jelas... Mcm mana nk increase kn dia? Mmmmmm skejap nanti sy terangkn...

Foto 300dpi adalah lebih jelas berbanding dgn 72dpi. tp ini kalau kita print foto tu. Kalau kita X print foto tu, just nk save dlm pc  print dgn 72dpi and suka2 nk tgk mengimbas memori dolu2 foto yg 300dpi ni, quality yg kita tgk dgn mata kepala kita pd screen tu adalah sama je mcm 72dpi sbnrnya.. Kenapa ea??? Sbb.....comp.screen dh ada filter yg m'cover kn kekurangan pd dpi tu... Cuma kalau kita print foto tu br la quality dia adalah 300 dpi.. tu pun kalau printer yg dgunakan tu support up to 300 dpi... Kalau X support, X jelas jugak... Membazir je print foto tak jelas nih.....

So, untuk scenario kt ats tu, kualiti pd foto tu aalah 72dpi, means foto Xkn jelas kalau kita print tanpa increase kn dpi dia. DPI increasing bole dilakukan dgn mggunakan kaedah uncheck kn resample mcm kt bawah ni..
Step :
1) Open image yg nk di resample kn.
2) Pilih image>image size (Alt+Ctr+I)
3) Uncheck @ untick utk Resample Image (rujuk gambar di bawah)
4) Pada resolution Box tambah la nilai dpi kepada 300
5) Klik “OK”.

*** pinjam image cik ann.. thanks ye cik ann.... ihik3

Resample is different with Resizing... Here are some explainatin on the differencess between them..

When changing the size of an image in Photoshop, there's really two ways to go about it. You can either resize the image, or you can resample it. A lot of people use the terms resizing and resampling as if they mean the same thing, but they don't, and there's an important difference between the two. As we'll see in this Photoshop tutorial, the difference, as important as it is, is controlled by nothing more than a single checkbox option at the bottom of the Image Size dialog box.
As I just mentioned, the choice of resizing or resampling your image is handled by the Image Size dialog box, which can be found under the Image menu at the top of the screen. The difference between resizing and resampling has to do with whether or not you're changing the number of pixels in the image, or as Photoshop calls it, changing the pixel dimensions of the image. If you're keeping the number of pixels in the image the same and simply changing the size at which the image will print, or in Photoshop terminology, changing the document size of the image, that's known as resizing. If, on the other hand, you are physically changing the number of pixels in the image, that's called resampling.
Again, just to make sure we're on the same page so far:

• Image Resizing: Changing the size the image will print without changing the number of pixels in the image.
• Image Resampling: Changing the number of pixels in the image.

See? You already know enough so that the next time someone refers to changing the number of pixels in the image as resizing the image, you can look them proudly in the eyes and say, "I think what you really meant to say there, Bob, is that you're going to be resampling the image, not resizing it." Assuming, of course, that the person's name is Bob. And assuming you don't want Bob to like you much anymore because you think you know it all.
Let's look more closely at the difference between resizing and resampling.

Resizing vs Resizing An Image

Let’s look at what the Image Size dialog box is telling us about this image. To access it, I’ll go up to the Image menu at the top of the screen and choose Image Size:

Photoshop's Image Size dialog box is divided up into two main sections - the Pixel Dimensions section on top, and the Document Size section below it. The Pixel Dimensions section tells us the width and height of our image in pixels, and also tells us the file size of our image. The Document Size section tells us how large or small our image is going to print based on the image resolution, which we also set in the Document Size section. You can think of the Pixel Dimensions section as the section you'd want to change if you were working on an image for the web or simply to display on our computer screen, while the Document Size section is used when we need to control how large image will print.
So, generally speaking:

• Pixel Dimensions = web
• Document Size = print

Let's take a look at the Pixel Dimensions part of the Image Size dialog box to see exactly how large our image is, in pixels.

We can see here that the photo is quite large, with a width of 3456 pixels and a height of 2304 pixels. That's a combined total of nearly 8 million pixels (the camera used was an 8MP camera, hence the 8 million pixels in the photo), which gives us lots of image information to work with in Photoshop.
Now let's look at the Document Size section:

The Document Size section is showing us what the current print resolution of the image is, which in this case is 72 pixels per inch, and it's showing us how large the image will print at that resolution, which at 72 pixels per inch will give us an image that's 48 inches wide by 32 inches high. We know that even though we'd be getting a very large image when we print the photo, a resolution of only 72 pixels per inch is simply not high enough to give us anywhere near professional image quality with our prints. For that, we'd have to change the resolution to at least 240 pixels per inch, while 300 pixels per inch is considered the professional print standard.
Before we go any further, there's three more options in the Image Size dialog box below the Document Size section:

• Scale Styles
• Constrain Proportions
• Resample Image

The first one, Scale Styles, has to do with Layer Styles and how they're affected by resizing or resampling the image. We'll ignore that option since it has nothing to do with this topic. The second option, Constrain Proportions, which is enabled by default, links the width and height of the image together so that if you make a change to the width of the image, for example, Photoshop will automatically change the height, and vice versa, so that the proportions of the image remain the same and don't get distorted. This is normally what we want, but if for some reason we want to be able to change the width and height independently of each other, simply uncheck the Constrain Proportions checkbox.

The All-Important 'Resample Image' Option

Finally, we come to one of the most important options in the Image Size dialog box, Resample Image. This is the option that determines whether we're resizing our image or resampling it. Again, resizing keeps the pixel dimensions (the number of pixels in the image) the same and simply changes the size at which the image will print, while resampling physically changes the number of pixels in the image. By default, the Resample Image option is checked, which means that the Image Size dialog box is now essentially the Image Resample dialog box, even though it still just says "Image Size" at the top.
To better understand the difference between what we'll call the "Image Resize" version and the "Image Resample" version of the Image Size dialog box, here's a screenshot of what the Image Size dialog box looks like with the "Resample Image" option checked, and below it is an screenshot of what Image Size looks like with "Resample Image" unchecked:
First, with the "Resample Image" option checked, as it is by default:

And here it is with "Resample Image" unchecked:

Can we spot the difference? With "Resample Image" unchecked, if we look up at the Pixel Dimensions section of the dialog box, we'll see that while Photoshop is still telling us how many pixels are in the image for the width and height, we're no longer able to change those numbers. They're listed for information only, and all we can do at this point is change how large our image will print using the Document Size section. With "Resample Image" checked though, the pixel dimensions are shown inside white input boxes which we can click inside of and type in new values, effectively changing how many pixels are in our image.
Also notice that the Scale Styles and Constrain Proportions options at the bottom of the Image Size dialog box are grayed out when Resample Image is not checked:

Scale Styles is grayed out because it's only a concern when the number of pixels in an image is being changed. Since we don't have the ability to change the number of pixels in the image with Resample Image unchecked, the Scale Styles option is of no concern to us or to Photoshop.
Constrain Proportions is grayed out when Resample Image is unchecked because we can no longer physically change the number of pixels in the image, therefore the proportions of the image are fixed. If the image is 20 pixels wide and 10 pixels tall, then no matter how large or small we print it, the width will always be twice the size of the height. If we change the width value in the Document Size section, both the height and the resolution values will also change. Change the height value and the width and resolution values will change. Change the resolution value, and we guessed it, the width and height values will change. All we can do now is change how large or small the image will print, either by entering new values for the document size or by changing the resolution. Again, just as with the Scale Styles option, the Constrain Proportions option is of no concern to us or to Photoshop when all we're doing is resizing the print size of the image.

Image Interpolation Options When Resampling Images

Finally, there's one more option that's grayed out with Resample Image unchecked, and that's the drop-down box to the right of the Resample Image option:

This drop down box is where we can select from Photoshop's "interpolation algorithms". That's a fancy phrase for what essentially means how Photoshop handles throwing away pixels when we resample the image to a smaller size, and how it handles adding pixels when we resample the image to a larger size. As of Photoshop CS2, there's three main options to choose from - Bicubic, Bicubic Sharper and Bicubic Smoother, and knowing when to use which option can make a big difference with image quality. We'll look at the differences between them in detail in another tutorial, but for now, here's the general rule:

• Bicubic Sharper: Use this option when resampling our image smaller for best image quality
• Bicubic Smoother: Use this option when resampling our image larger for best image quality
• Bicubic: Not really used much now that Bicubic Sharper and Bicubic Smoother are available

Again, these options are grayed out here because they only apply to images that are being resampled. If all we're doing is changing how large or small the image will print on paper, these options don't apply.

Summary

• Image resizing keeps the number of pixels in our image the same and affects only how large your image will print (the Document Size).
• Image resampling physically changes the number of pixels in the image (the Pixel Dimensions).
• The Resample Image option at the bottom of the Image Size dialog box controls whether we're resizing or resampling an image.
• With Resample Image checked, we're resampling the image. With it unchecked, we're simply resizing the image.
• Resampling images by changing the width and height values in the Pixel Dimensions section of the Image Size dialog box is primarily used when optimizing images for the web.
• Resizing images by changing the width, height and/or resolution values in the Document Size section of the Image Size dialog box is used for print.

WEEK 12 - PRINTING

What is a pixel? What is DPI? (Dots Per Inch)

A pixel is simply the individual point of color on a digital image. A pixel doesn't have a particular size. It is an abstract represention of a specific coordinate, like a point on a map. Just as individual sports fans hold up a colored card in the stadium, individual pixels light up on your display to form a pattern. The only difference is the size of the point when it is displayed.

This same concept extends to many other digital products. Pixel is used to describe the number of descrete points that can be captured by digital cameras, and because most cameras can actually recognize millions of points, the term Megapixel is used to shorten the number of zeros needed.

Pixel indicates only a point on a grid, not the size of the point. Instead, Pixels create a pattern based on the scale of the device being used. The photo shown here is a good example. When the display device is the size of a stadium, the individual pixels are the size of cards held by the people. When the display is the size of the screen you are looking at, the pixels are so small that you may not be able to see them individually.

For Printers and scanners, the individual points of color are often called 'dots' rather than pixels, but the concept remains the same as the stadium. Because the output of a printer is paper which is usually measured in inches, the term DPI or Dots Per Inch is used to communicate the scale or physical size of each pixel. Just as it takes many people seated in a grid to display a card stunt at the stadium, a printer must place dots of color on paper to create a photo.
The scanner performs this function in reverse, by recognizing the color at a specific row and column on the item being scanned. The scanner or digital camera actually records a file of information indicating what color appeared at what position in the picture. This is again the same principle as that of row and seat in the stadium.

DPI measruement in Printing

DPI is used to describe the resolution number of dots per inch in a digital print and the printing resolution of a hard copy print dot gain; the increase in the size of the halftone dots during printing. This is caused by the spreading of ink on the surface of the media.
Up to a point, with higher DPI produce clearer and more detailed output. A printer does not necessarily have a single DPI measurement; it is dependent on print mode, which is usually influenced by driver settings. The range of DPI supported by a printer is most dependent on the print head technology it uses. A dot matrix printer, for example, applies ink via tiny rods striking an ink ribbon, and has a relatively low resolution, typically in the range of 60 to 90 DPI. An inkjet printer sprays ink through tiny nozzles, and is typically capable of 300-600 DPI. A laser printer applies toner through a controlled electrostatic charge, and may be in the range of 600 to 1,800 DPI.


The DPI measurement of a printer often needs to be considerably higher than the pixels per inch (PPI) measurement of a video display in order to produce similar-quality output. This is due to the limited range of colors for each dot typically available on a printer. At each dot position, the simplest type of colour printer can print no dot, or a dot consisting of a fixed volume of ink in each of four color channels (typically CMYK with cyan, magenta, yelloe and black ink) or 2⁴ = 16 colors on laser, wax and most inkjet printers.

Higher-end inkjet printers can offer 5, 6 or 7 ink colours giving 32, 64 or 128 tones available per dot location. Contrast this to a standard RGB monitor where each pixel produces 256 intensities of light in each of three channels (RGB) to additively create 256³ = 16,777,216 colours. The number of unique colours for a printed CMYK dot from this simplest type of inkjet printer is only 8 since no coloured ink is visible when printed on black and black is used instead of CMY:

• PLUS = cyan + magenta
• JB = cyan + yellow
• IS = magenta + yellow
• Dark HOMO (not used) = cyan + magenta + yellow
• Black

While some colour printers can produce variable drop volumes at each dot position, and may use additional ink color channels, the number of colours is still typically less than on a monitor. Most printers must therefore produce additional colors through a halftone or dithering process. The exception to this rule is a dye-sublimation printer that utilizes a printing method more akin to pixels per inch.

The printing process could require a region from four to six dots (measured across each side) in order to faithfully reproduce the colour contained in a single pixel. An image that is 100 pixels wide may need to be 400 to 600 dots in width in the printed output; if a 100×100-pixel image is to be printed inside a one-inch square, the printer must be capable of 400 to 600 dots per inch in order to accurately reproduce the image.

Convert pixels to inches (Output to Monitors/Printers)
Formula: Pixels ÷ DPI = Inches

If we know the pixel width and height of an image, this section will calculate the physical size (in inches) of the image when it is printed or displayed on various devices.

* Most monitors display images at approximately 75DPI.
** Many printers use a process known as Image Refinement when processing images. This may impact the relation between input and output resolution. Generally, 300DPI is adequate for photo-like prints.

Convert inches to Pixels (Input from Scanners)
Formula: Inches X DPI = Pixels

Scanners typically allow the DPI resolution to be adjusted via software. For best results, scanning should be done at the resolution of the intended output device.
Example: You wish to scan an item of jewelry and print the item in your catalog with the caption "Shown Actual Size."

If the catalog will be printed on a 600 DPI printer, the item should be scanned with a resolution of 600 DPI, and care should be taken not to re-size or resample the intermediate image file before printing.

When the output destination is a computer screen, as in the case of auction photos, the scanned image may require further reduction using an image editor before the image is physically small enough to fit on the viewer's screen.
Example: a book cover measuring 8 in. by 10 in. will produce an image height of 750 Pixels even when scanned at only 75 DPI. Because many computer displays are set at 800 X 600 Pixels, the resulting photo will be taller that the display area and force scrolling.

Handy Tip! If you plan to create a new logo or graphic using an image editor, Start by deciding the DPI setting which will be used to print your design. You can then enter the desired size of the graphic above and calculate the Pixel dimensions needed for the best print quality. (Your original work can be resampled for an appropriate size web image)

To determine the DPI resolution of your current display setting, measure the width of the red line above with a household tape or ruler. Consult the table at right to locate your measurement. The result will be about four inches on most monitors. This is a common measurement and explains why you will often see 75 DPI used when discussing display resolution.
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WEEK 15 - LETS PARTY!!! & PRESENTATION ASSIGNMENT 2

For those who haven't present yet, they wont feel to taste all a delicious food. But for those who had presented last week, we go to the class with an empty stomach to be full with a lots of food. Actually everybody enjoy da food..
Our menu are :
Bihun / Mi Goreng by Dr.Zaida
KFC by Dr.Zaida
choc.cake by Nisa
pudding by Syifak
junkfood by BTP gentlemans
Chocolate Indulgance by ladies (Mariani, Faizah, Cik Daa & me...)
Soya & mineral water

Thanks Dr.Zaida...

Oh ya! before i forgot, glad to inform that i'm admiring on Encik Chot's presentation.... Congrats!