Bizarre font size problem in VB.net

[xoggoth]

Have a program that was all tested out and I have not changed the code, just the images displayed. It still works ok with the previous set of images. Marking some images with an "X" in one corner but it is drawing at a huge fontsize although the debugger tells me the fontsize is as expected. With a test copy to clipboard added just to make sure I am not doing something daft later on, the relevant code is:

Private scratch As New PictureBox
Private gr1 As Graphics
...
gr1 = Graphics.FromImage(scratch.Image)
gr1.DrawString("X", MainBox1.Font, Brushes.Red, pr.PicTX, pr.PicTY)
My.Computer.Clipboard.Clear()
My.Computer.Clipboard.SetImage(scratch.Image)

Debug tells me that MainBox1.Font = {Name = "Arial" Size=12.0} but when I open the clipboard my "X" is more like fontsize 180!!! Drawline etc also comes out similarly enlarged. The sizemode of scratch is normal.

I can't think of any reason and can't find owt useful on net so grateful for any suggestions on this.

[xoggoth]

Have asked a few questions on net and it has been suggested the internal resolution of pictures is too high. PSP reports images that work as 508 pixels/inch, ie 832x690 pixels, 1.638x1.358 inches and ones that don't as 71 pixels/inch, ie 832x690 pixels, 11.702x9.705 inches.

I really have no idea what that means as they look the same.

[Joe Black]

The issue of dpi can certainly be a factor, if I'm correct in that the new ones have a higher perceived resolution.

Font sizes, as you might have discovered by now, are usually (though not always) specified in points/parts of an inch. If the image is considered to be 508 dpi then of course the font is scaled as appropriate.

Had a similar problem not too long ago with some jpegs where the EXIF data was corrupted somewhere along the way and the dpi ended up at 24000 horizontal, 600 vertical, resulting in them being displayed as one pixel lines when viewed as thumbnails.

If that's the case then you simply need to open and resave the images with the correct/adjusted dpi in Photoshop/Paintshop Pro, or if they're jpegs already and you don't want to lose quality then do a Google for an EXIF tool. Usually 96dpi is the case for MS, 72 for Macs.

[xoggoth]

Ta Joe, have solved it by pasting into Paint and resaving. They still look exactly the same.