How do I increase image dpi and preserve quality?

I knew you can easily change lower dpi to higher dpi by photoshop. Image %26gt; Image Size

By doing this, you are going to lose your quality.

However, most of my image size is large enough. I am just wondering is it possible to trade off between size and quality.

All I am trying to say will the quality preserve if I increase dpi but decrease my photo size?

If this is doable, is there a software to do so?



For example,

increase dpi from 100 to 300.

change 300 x 300 image to 100 x 100 dimension.

Will the quality preserve?



Thanks in advance,How do I increase image dpi and preserve quality?
When you reduce the size the number of pixels per inch will increase. You don't lose any quality, the resolution goes up. You can see that in Photoshop when you change the size.



Additional Details

You are making this harder than it is. Forget dpi, we are talking about pixels which are ppi. Even if your printer calls it dpi they mean ppi, printers use dpi in place of ppi because people use the terms incorrectly and they think it makes it easier to communicate. If you are using Photoshop you need to use the correct term because that is what Photoshop uses.

Go to Image/Image Size and look, you will not find dpi in there. Take a look at this http://www.youtube.com/watch?v=qu5adJfxuhw , see how you can type in the pixel dimension you want (300) and see what the Document Size changes to. If that size is equal to or larger than what you want there is no problem. If it is smaller than you want you will lose image quality making it larger. At the size you want to print your printer should let you submit the image at a lower resolution - 240ppi would be acceptable if it is a good image. Ask them.

Learn this http://www.photoshopessentials.com/essentials/image-resizing.php and http://www.photoshopessentials.com/essentials/resizing-vs-resampling.php if you don't get it after that find someone to do it for you.How do I increase image dpi and preserve quality?
there is some merit to minimizing visual size and keeping print quality, but if image is only 300 pixels @100 * dpi for print option, there may be no reason to shrink image,



note dpi is print quality as opposed to ppi for pixel quality, so when you have image at unknown 300 ppi, this is separate from dpi options to print,



also note format of image if tif or raw, compared to jpg or png, the quality of bits may alter when resized, and the setting for compression rate when saved at highest % quality,



so increasing dots per inch for print, may not preserve output for image more or less, shrinking image 300 to 100 pixels lowers amount of information per pixel, in a sense you are removing 2 of 3 pixels in a row

and the amount of dots used to print that pixel would not know of any other pixels that were missing, and the bit depth for colours would be narrowed to one,



if you have photoshop try a large sample, and make copies,

save with compression,

save with image size in inches,

save with pixel size

save with resample ratio

save as other format tif/ jpg/ eps



not to print, only for viewing depending on sizes and colours,

..