no bug Resolution bug in RIOT-plugin

[cosmicgirl]

The RIOT-plugin could be a nice feature for IrvanView but it seems like a mistake happened by implementation of the stand-alone RIOT version.
Anytime I compress a 96-dpi-picture with this plugin the picture would have a resolution of 72 dpi after compression.
However, the original RIOT-tool preserves the 96 dpi after compression.

[Skippybox]

This does not seem transparent to me. Can you tell us what version of RIOT (standalone and plugin) you are using (e.g. 0.3.3 Lite or Extended plugin)? And what format the input and output is?

[cosmicgirl]

Operating system: Windows XP Pro, SP2
IrfanView 4.25 with RIOT.DLL 0.3.3.0 (Light Plugin)
RIOT standalone: Version 0.3.3

Input format = JPEG
Output format = JPEG

[luciansabo]

This is not a bug.

The dpi is used only for printing. It is not the purpose of RIOT to save files made for printing. For printing it is recommended a format that supports lossless compression. JPEG is not a good choice for this, unless you take the image straight from the digital camera and the digital camera does not have another compression method.

However, RIOT keeps this information.
For the RIOT plugin all you have to do is go to Tools->Options , RIOT plugin tab and check "Import ancillary data from original file".

For short: this gets the dpi value from the original image.

Technical explanation:
When used as plugin the image is sent as DIB. DIBs do not contain any other informations than RGBA pixels. Unfortunatelly IrfanView does not use 32 bit data, only 24 - and the transparency is not sent. If a file exists, metadata, transparency, dpi and ICC profile from original file will be imported if the program is set to do it.

[MItaly]

The DIB contains the resolution of the image in the BITMAPINFOHEADER header, in the biXPelsPerMeter and biYPelsPerMeter fields. Note that the DIB supplied by IrfanView specifies these values in DPI instead of pixels per meter.

[luciansabo]

You're right about the bitmap info header. I will check again the import function. If this info is accurate like you say, I can take it from the bitmap info header, without the need to import from file.

[luciansabo]

In the next version (0.3.4) the resolution is taken from the DIB so this problem will go away.

Thank you, MItaly for the valuable info

[MItaly]

Glad of having been helpful.