est said:
I have a document in publisher which includes a photo which i am
trying to send to someone to be used as an advert in a publication -
they say the resolution is too low and have asked me to change the
dpi to 300.
Unless you are exporting from Publisher 2002 as an image, or exporting as a
low-res image from Publisher 2003, the person almost certainly means the DPI
of your photo.
The DPI is a measure of the number of pixels in one inch in the vertical and
horizontal directions.
If you have a 150dpi image, then for each inch of printed length, you have
150 pixels. Each inch of printed width is also 150 pixels.
If you want to retain the same printed size, and increase the resolution to
300dpi, you need to have 300 pixels for each inch in the vertical and
horizontal directions. This means you need FOUR TIMES as many pixels. Only
one quarter of these pixels will have information available for them.
e.g. For a very small image, scaling from 150dpi to 300dpi
Original:
ABCDEFGH
IJKLMNOP
QRSTUVWX
YZABCDEF
GHIJKLMN
OPQRSTUV
WXYZABCD
EFGHIJKL
Final:
A?B?C?D?E?F?G?H?
????????????????
I?J?K?L?M?N?O?P?
????????????????
Q?R?S?T?U?V?W?X?
????????????????
Y?Z?A?B?C?D?E?F?
????????????????
G?H?I?J?K?L?M?N?
????????????????
O?P?Q?R?S?T?U?V?
????????????????
W?X?Y?Z?A?B?C?D?
????????????????
E?F?G?H?I?J?K?L?
????????????????
The computer has no idea what goes into the spaces marked ?. Neither does
your printer or anyone else in the world.
Solutions:
a) Resize the picture to a smaller print size - this increases the pixel
density so that there are more pixels per inch.
b) Find a higher-resolution version of the photograph.
c) Replace the photograph with a different or similar one of a higher DPI
d) (NOT RECOMMENDED) Resample the image in a graphics program to make it
look as if it has a higher DPI (although in effect this is pointless and
will blur your image, as well as annoying your printer) - this will not have
the effect that your printer intends, and will look bad.
