export with "bmp" format with standard DPI headers

**rpc9943** · 31 May 2011, 04:47 PM

This is quite specific because my employment is using software that is specialized for use with BMP's. I am not sure why we do not have the option to set the DPI header upon export. Every other software I have used includes this.

Thank you
RonC

**Soquili** · 31 May 2011, 04:54 PM

Ron can you attach a screen shot of any software's option to set a bmp dpi header?

I don't recall ever seeing one.

Microsoft bitmap images (.bmp) has always been a default of 96 dpi (standard windows resolution).

**Soquili** · 31 May 2011, 05:03 PM

This link shows the Windows bitmap file structure. http://www.fileformat.info/format/bm...86d9c/view.htm

The header specification does not include any dpi information that I can find.

**Soquili** · 31 May 2011, 05:10 PM

Maybe you are referring to a .dib (device independant bitmap)? File structure: http://www.fileformat.info/format/bm...c67a4/view.htm

The .dib still image format contains an embedded jpeg image which does support a dpi.

**Soquili** · 31 May 2011, 05:39 PM

It appears there is a resolution for Target Device in the BITMAPINFOHEADER structure.

The values are normally set to zero although it is possible to set the number of pixels per meter that the target device supports.

The biXPelsPerMeter is used for Horizotal resolution and biYPelsPerMeter for the Vertical resolution. Both refer to a specific target device resolution. An application can use those values to determine a specific bitmap within a resource group to send to a specific target device.

The display screen is usually the target device for a .bmp image so the biXPelsPerMeter and biYPelsPerMeter are set to 0 by current applications creating an individual bitmap image for display.

I'm not aware of applications that are created to support output devices that work using Pixels Per Meter, although it sounds like a good feature for (extremely) large format printers designed for billboards.

**rpc9943** · 31 May 2011, 05:59 PM

I can define further what I mean once I talk to my boss, he codes the software for this so he's pretty familiar with the .bmp file...

**GerryI** · 31 May 2011, 10:44 PM

Don't worry, we know all about the PelsPerMeter settings. The value equivalent to 96dpi is 3780 (actually 3779.53). Writing different values into these fields in a BMP used to (i.e. more than 10 years ago) cause many more problems than it solved but we should probably look at it again.

Gerry

**Soquili** · 01 June 2011, 01:45 AM

Thanks Gerry, I wasn't worried.

If the issue of setting values other than zero in those fields were resolved I think it would have been significant enough to have been heard around the world.

**rpc9943** · 01 June 2011, 03:40 PM

Here's what I mean, if you can access a program such as photoshop, you can see what I mean. You can open a .psd file with dpi for example of 300, and then export it as bmp. Reload the bmp into photoshop and do image properties and it will show 300 dpi. If you do this with a .psd file of a dpi of 600, and export, load bmp, and it will show 600 dpi in the image properties.

**mwenz** · 01 June 2011, 04:52 PM

I think there is a difference between vector and bitmap formats as far as designing and exporting going on here. Not that XDP should not be able to allow for this. But the vector design is resolution independent. Combined with the fact that XDP doesn't allow the change in bitmap (BMP format) resolution directly. I.e., left by itself XDP wants to export at screen resolution and the drop down for changing this is disabled.

So, I loaded a card design, a TIFF that is 300 dpi.

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I then loaded this TIFF into XDP7. When I go to export, this is what I see:

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Note the resolution XDP wants to export at. Not good as I already know the dimensions from loading the TIFF version into my bitmap editor. And I cannot simply choose the DPI drop down.

Knowing the dimensions I desire, though, I can then type them into the appropriate dialog box as so:

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When I set the dimensions upon export, the graphic is reported at the size it was desired to be and is thus reported when I load the BMP version into my image editor:

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Perhaps I have misunderstood. But this seems to work "fine." XDP cannot "know" what one's export intent is. It *can* be made to realistically allow setting these options a little easier, more intuitive though.

Choosing to work in pixels as units is a must for this type of work. Combined with the settings to the desired dimensions seems to end up as a work-around for not being able to set the BMP DPI directly.

Take care, Mike