Requested Adjust threshold when converting to black and white (2 tone)

[Mowgli Diani]

Hi

When converting to black and white (2 tone, not grayscale) I think it would be nice to be able to adjust the threshold of what will become white, and what will become black.

I have not found this in IrfanView, it chooses on its own.

I know that there's a plugin available for that but it has some shortcomings, and I feel that this feature seems basic enough to be in the main IrfanView version.

Thanks

[Skippybox]

You could try palette editing.

Need help converting scans

[Sam_Zen]

Right on, Skippybox.

And thinking about it, I guess a direct conversion of some bitmap to B&W will be just too drastic anyway.
Even the use of those thresholds will not guarantee a correct result.

Pixels being in the 'doubt' zone often are situated at the edges of strong contours.
The choice whether a pixel belongs to the 'object' or to the background is quite tricky to program.

The chance is, that after setting thresholds, the result will yet have to be checked on irregularities, and set again.

So sometimes the trick with palette editing will be more efficient. Decrease colors to four, then correct the two at the center of B and W.

[rosive]

I agree with Mowgli Diani.
It would have been useful to be able to specify the threshold value when converting images to black and white (from color and from grayscale).