U++ forum: Welcome to the forum

Status & Roadmap

Authors & License

Funding Ultimate++

Search on this site

Search in forums

Home » U++ Library support » Draw, Display, Images, Bitmaps, Icons » How to set the dpi (dots per inch) of an image

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Return to the default flat view

Create a new topic

Submit Reply

Re: How to set the dpi (dots per inch) of an image [message #27584 is a reply to message #27562]

Sat, 24 July 2010 11:08

koldo is currently offline

koldo
Messages: 3356
Registered: August 2008

Senior Veteran

luzr wrote on Fri, 23 July 2010 11:37

koldo wrote on Mon, 19 July 2010 04:03

luzr wrote on Sat, 17 July 2010 09:58

koldo wrote on Thu, 15 July 2010 05:07

Hello all

I have loaded a scanned image, processed it and saved it. The original image had 300 x 300 dpi, but saved image has 96 x 96 dpi.

Is it possible to set the saved image to 300 x 300 dpi?

RasterEncoder::SetDots - you set the "physical" dimensions of Image there.

The only problem is that real encoder has to use this value. I did now a quick review, looks like bmp and png do, jpg has it commented out for whatever reason, gif ignores the value. But all seems to provide it for Raster::GetInfo.

Mirek

Hello Mirek

I have tested it only with .png files using different SetDots values and the result is always the same:

- In Microsoft Paint it always appears 96 dpi hor. and 96 dpi vert.
- In XnView, it is like there is no resolution info (while original unprocessed .png file has dpi info).

Do you think you can look into the issue?

I believe that what is missing is just one call to

http://refspecs.freestandards.org/LSB_3.1.0/LSB-Desktop-gene ric/LSB-Desktop-generic/libpng12.png.set.phys.1.html

in

void PNGEncoder::Data::Start(Stream& stream, Size size_, int bpp, ImageKind kind_, bool interlace_,

Mirek

Hello Mirek

You have do it all. Adding this in Start function it works:

unsigned xdpi = 300;
unsigned ydpi = 300;
unsigned xres = unsigned(xdpi / 0.0254 + 0.5);
unsigned yres = unsigned(ydpi / 0.0254 + 0.5);
	
png_set_pHYs(png_ptr, info_ptr, xres, yres, PNG_RESOLUTION_METER);

The question is how to set xdpy and ydpi in U++ code.

Best regards
Iñaki

Report message to a moderator

Send a private message to this user

[Message index]

		How to set the dpi (dots per inch) of an image By: koldo on Thu, 15 July 2010 11:07
		Re: How to set the dpi (dots per inch) of an image By: mirek on Sat, 17 July 2010 09:58
		Re: How to set the dpi (dots per inch) of an image By: koldo on Mon, 19 July 2010 10:03
		Re: How to set the dpi (dots per inch) of an image By: mirek on Fri, 23 July 2010 11:37
		Re: How to set the dpi (dots per inch) of an image By: koldo on Sat, 24 July 2010 11:08
		Re: How to set the dpi (dots per inch) of an image By: koldo on Mon, 26 July 2010 09:50
		Re: How to set the dpi (dots per inch) of an image By: mirek on Fri, 13 August 2010 11:13
		Re: How to set the dpi (dots per inch) of an image By: koldo on Fri, 13 August 2010 13:46
		Re: How to set the dpi (dots per inch) of an image By: koldo on Sun, 22 August 2010 23:51
		Re: How to set the dpi (dots per inch) of an image By: mirek on Wed, 08 September 2010 09:17
		Re: How to set the dpi (dots per inch) of an image By: koldo on Fri, 10 September 2010 11:41
		Re: How to set the dpi (dots per inch) of an image By: koldo on Fri, 10 September 2010 13:42
		Re: How to set the dpi (dots per inch) of an image By: mirek on Mon, 13 September 2010 17:33
		Re: How to set the dpi (dots per inch) of an image By: koldo on Mon, 13 September 2010 21:56
		Re: How to set the dpi (dots per inch) of an image By: koldo on Tue, 14 September 2010 09:51
		Re: How to set the dpi (dots per inch) of an image By: koldo on Wed, 15 September 2010 09:17
		Re: How to set the dpi (dots per inch) of an image By: koldo on Wed, 15 September 2010 13:38
		Re: How to set the dpi (dots per inch) of an image By: koldo on Wed, 15 September 2010 15:02
		Re: How to set the dpi (dots per inch) of an image By: mirek on Thu, 16 September 2010 23:49
		Re: How to set the dpi (dots per inch) of an image By: koldo on Fri, 17 September 2010 09:58
		Re: How to set the dpi (dots per inch) of an image By: koldo on Fri, 17 September 2010 10:39
		Re: How to set the dpi (dots per inch) of an image By: mirek on Fri, 17 September 2010 20:17
		Re: How to set the dpi (dots per inch) of an image By: koldo on Fri, 17 September 2010 22:29

Previous Topic:	Icon at right side of the menuBar
Next Topic:	GetExifThumbnail doc

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

PDF

]

Current Time: Sat Apr 20 02:18:27 CEST 2024

Total time taken to generate the page: 0.06458 seconds