Sumatra PDF, though mainly used as a native PDF reader, DJVU, and EPUB reader, also has the functionality to open most image formats and automatically refresh the viewer:

PDF (.pdf) eBook formats: unencrypted EPUB (.epub) MOBI (.mobi)

Fiction Wise (.fb2, .fb2z, .zfb2) .pdb (Palm DOC format) .tcr

Comic book files: .cbz, .cbr, .cbt, .cb7z DjVu (.djv, .djvu)

Microsoft Compiled HTML Html (.chm) XPS (.xps)

Images (.tga, .gif, .jpg, .j2k,> .png, .webp, .tiff)

It doesn't lock the file if any other program is processing it.

Further usage documentation can be found here.

Sumatra PDF, though mainly used as a PDF reader, DJVU reader, and EPUB reader, can also open most image formats and automatically refreshes the document view, without locking the document if any other program is processing it. Quoting its web page, it opens:

PDF (.pdf) eBook formats: unencrypted EPUB (.epub) MOBI (.mobi)

Fiction Wise (.fb2, .fb2z, .zfb2) .pdb (Palm DOC format) .tcr

Comic book files: .cbz, .cbr, .cbt, .cb7z DjVu (.djv, .djvu)

Microsoft Compiled HTML Html (.chm) XPS (.xps)

Images (.tga, .gif, .jpg, .j2k,> .png, .webp, .tiff)

You can find further documentation at https://www.sumatrapdfreader.org/manual.html.

Sumatra PDF, though mainly a pdf, djvu, epub reader, also opens most image formats and automatically refreshes. It doesn't lock the file if any other program is processing it.

Sumatra PDF, though mainly used as a native PDF reader, DJVU, and EPUB reader, also has the functionality to open most image formats and automatically refresh the viewer:

PDF (.pdf) eBook formats: unencrypted EPUB (.epub) MOBI (.mobi)

Fiction Wise (.fb2, .fb2z, .zfb2) .pdb (Palm DOC format) .tcr

Comic book files: .cbz, .cbr, .cbt, .cb7z DjVu (.djv, .djvu)

Microsoft Compiled HTML Html (.chm) XPS (.xps)

Images (.tga, .gif, .jpg, .j2k,> .png, .webp, .tiff)

It doesn't lock the file if any other program is processing it.

Further usage documentation can be found here.