Now I tried both a linear tif and one with the original Canon TRC, both otherwise unprocessed. Scanin runs and outputs .ti3 files of 49 kB. But when I feed them to colprof, the Terminal text shows peak/average errors in the range 500 000/250 000! I have earlier gotten around 6/1.8. The output of colprof is a file with a generic icon, upon double-click I see hieroglyphs. The .tifs look about as exspected. The exact commands were: linear: ./scanin -v9 -dipn -p -a -G1.0 -F14.81,8.46,128.56,9.20,128.78,90.20,14.39,90.31 5D2_938_lin_HB0_0CM_exp+0,5.tif ColorCheckerSG.cht ColorCheckerSG_Graeme.cie ./colprof -v -ACanon -M5D2 -D5D2_938_lin_exp+0,5 -qu -al -y -bn -u -O5D2_938_lin_exp+0,5 5D2_938_lin_HB0_0CM_exp+0,5 with Canon TRC preserved: ./scanin -v9 -dipn -p -a -F15.44,8.57,129.26,9.31,129.58,90.20,15.23,90.42 5D2_938_CanCurv_0CM_exp+0,5.tif ColorCheckerSG.cht ColorCheckerSG_Graeme.cie ./colprof -v -ACanon -M5D2 -D5D2_938_curv_exp+0,5 -qu -al -y -bn -u -O5D2_938_curv_exp+0,5 5D2_938_CanCurv_0CM_exp+0,5 Sigh! - Hening