Effect of changing DPI

[tringhenge]

When I save jpgs from CS3 they are 240DPI. If I change the image to 300DPI in the image resizing window, does this lessen the quality of the image? If yes, is there another way to change the DPI to 300 before saving the jpg?

[dang]

I'd suggest reading here: http://graphicssoft.about.com/od/aboutgraphics/l/blscanning3.htm
Hope it helps.

[tringhenge]

Many thanks for the pointer.

[ken_bat]

Changing a file from 240dpi to 300dpi will not have any effect on image quality, but it will change the document (print output) size, reducing it by an amount equal to the percentage of dpi increase. To retain the original output size, you must resample the file — that is, up-size it. In Photoshop you can do this in the Image Size dialogue window. (Image>Image Size)

In this case, check off the Resample Image box only and change the resolution from 240 to 300. You'll notice that the Pixel Dimensions will increase as a result of the resampling — which means the overall file size will increase as well.. When up-sizing like this, make sure the Bicubic Smoother option is selected in the drop down menu.

This procedure will retain the original document/output size, but with a resolution increase from 240dpi to 300dpi.

I hope this answers your question.
Ken

[tringhenge]

Cheers for that Ken, appreciated.