Question

How to retain the resolution of an image while reducing or expanding… Is there a way…

Answer 1

You shoould check here, same problem exists:

http://forums.oracle.com/forums/thread.jspa?threadID=1270008

Solution offered there:

TIFFEncodeParam tep = new TIFFEncodeParam();

// Create {X,Y}Resolution fields.
TIFFField fieldXRes = new TIFFField(0x11A, TIFFField.TIFF_RATIONAL,
                                1, new long[][] {{DPI_X, 1}});
TIFFField fieldYRes = new TIFFField(0x11B, TIFFField.TIFF_RATIONAL,
                                1, new long[][] {{DPI_Y, 1}});
tep.setExtraFields(new TIFFField[] {fieldXRes, fieldYRes});