How to increase the DPI

Hello all,

I would like to have a clear idea of how I can send images to the print office. I sent them as 72 dpi and they asked me
to increase it to a better dpi quality. I want to print some brochures so the images should appear crystal clear.
The size of the my prochures is 800x600 pixels. I would like to keep this size but increase the dpi.

Could anyone explain me the concept behind this and how I can increase the quality?

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Think of it like this: your image is essentially a bunch of squares, like graph paper. The more squares you have, the smaller the squares are, and the more detail you have. The fewer squares you have, the less detail and the more jaggy things like curved objects look, and fuzzier detail. If you start with large squares, no matter how small you change the resolution to, you will still have large squares made of smaller squares.

You really need to capture high resolution/dpi images FIRST (usually a minimum of 300 dpi). You can try to increase the resolution of your images and then sharpen them, but I suspect you won't get what you want.
nectarios777Author Commented:
How would I do that?
Lets say I take a picture with my 7 megapixel camera. How do I know how many dpi does it have?
Your camera should have come with a manual that tells you how to take the highest resolution picture possible - I do not know what your camera is, but it should be something you can easily change. It sounds like you have it set on low resolution at the moment. Be forewarned, the higher the resolution, the larger the file size, and the less total pictures you will be able to take on one card.
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nectarios777Author Commented:
Ok, the question is how do I convert my 800x600 document to 300 dpi without changing its dimensions?
You can do that in photoshop easily, but it won't improve your image. Just to to Image > Image Size.

Make sure Constrain Proportions and Resample Image are check as on, and change your resolution to 300 dpi. You may want to play with the different types of resampling, I always thought Bicubic was best, but I have heard differing opinions.
take a picture from your camera in full size (largest one) because most camera have 72 dpi images.

now, what you have to do is take a photo as large as you can if you are concern with print quality.

set your design canvas (your brochure) to have 300dpi. it won't change the print size of your file so dont worry if it looks bigger or smaller in your screen. what you just did is inserts more pixels in your design to increase the quality of printouts. 300 dpi is widely used printing quality resolution.

now insert your image in your design canvas and resize it to your needs.  take note, resize your photo in your design canvas not seperately in order to make sure of its proportionality in your design.

if your brochure print size is 4inches by 6inches, incresing your dpi will inserts more pixels inside that size, hence, result in to higher print quality.

dpi stands for dot per inch.

if you have 4 inches width in 72 dpi, that means you have (72x4) dots across your design

if you have 4 inches in 300 dpi, that means you have (300x4) dots accross your design

as a result, dots becomes unnoticeable and makes your image smoother


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