Hi Ale870,
Rofar wrote:A free (open source) alternative to Photoshop is The Gimp. Also, Paint.NET is a nice lighter weight program that should be able to do it.
Oops, not true. Paint.NET and the GIMP
do not support 16-bit colour depth, and both will convert 16-bit files to 8-bit [This was tested with GIMP v2.4.5 and Paint.NET v3.36.]
ale870 wrote:The problem is I didn't save that image with IrfanView! test.png is the original image L3DT created.
This I know. The 'test.png' file you sent me is the one I tested in Photoshop, Opera, IrfanView, and L3DT itself, and they all reported that the file is 16-bit (although IrfanView converted it to 8-bit in memory, as is its wont). By the way, as Brad mentioned, Vista also thinks your 'test.png' file is 16-bit:
In conclusion, the file exported by L3DT was 16-bit. If it ended up with 8-bit stepping, it's probably because Picture Pro converted the image to 8-bit in memory before saving it out as a 16-bit TIFF.
ale870 wrote:Well, please help me to take another way. I haven't money to buy Photoshop (furthermore I'm a programmer, even if I buy it I will never heavily use it). So can you suggest me another program to make that conversion?
ImageMagick seems to be able to convert files at 16-bit precision (
see this forum thread). It's a command-line program, but it is excellent.
ale870 wrote:One more test (last one): please can you create a png file with L3DT and send me that? (maybe I have some problems with one internal DLL or shared DLL, etc...).
It won't be any different to the file you created in L3DT, which was also 16-bit. But for completeness, here you go:
The same programs that told you that your test.png file was 8-bit will also now tell you that the above image is 8-bit too. They are wrong, for the reasons we've explained. If you'd like to prove this to yourself, I recommend you download
libpng and read the PNG file header yourself.
For the sake of comparison,
here is the same image saved as 8-bit. Note that the 16-bit image is 365kB, whilst the 8-bit file is only 57kB.
Cheerio,
Aaron.