no bug Color JPG displayed in grayscale

[yao312]

Hello.
I use irfanview ver.4.57 64bit.
Attached color photos are displayed in grayscale.
Is this problem caused by irfan or jpg data?
Windows 11 thumbnail is color, but displayed in grayscale when I open by some photo viewers.

[j7n]

In the settings of IrfanView under JPG / PCD / GIF there is an option for loading all images as grayscale. And on the Save As dialog there is an option to discard color. It is possible that your photos had been edited, but the thumbnail was copied over from the original and thus retained color. Do any photo viewers open them in color?

These 2 samples have been recompressed and don't have a thumbnail anymore.

[yao312]

Thank you for the reply.
I think you are correct.
Maybe I overwrote them by mistake in grayscale setting.