Limited picture size (previews in Konqueror, kview)?

Hello all, I'm running Trinity (latest stable) on openSuSE 12.3. In Konqueror (file management). It seems I can get previews for "smaller" pictures (up to at least 4896x3264 pixels), but not for larger ones (7216x5412). Gimp loads these, kview does not, neither can Gwenview. However, if I load the pictures in the Ristretto Image Viewer (that obviously creates thumbnails for it's own use), then refresh in Konqueror, I get the previews. So I guess there is some limit with the "engine" used for picture viewers in Trinity? I must check, but I think it worked OK with the KDE 3 from openSuSE, maybe I'm wrong. Note that I _did _ check the settings in configure-konqueror - Previews & Meta-Data and set the maximum file size at 100MB, to test (the files are around 5 MB jpg), it did not change anything, Thierry