diff --git a/rtengine/imageio.cc b/rtengine/imageio.cc
index f869a0f3e..e886dabce 100644
--- a/rtengine/imageio.cc
+++ b/rtengine/imageio.cc
@@ -556,11 +556,13 @@ int ImageIO::loadJPEG (Glib::ustring fname)
         jpeg_read_header(&cinfo, TRUE);
 
         //if JPEG is CMYK, then abort reading
-        if (cinfo.jpeg_color_space == JCS_CMYK || cinfo.jpeg_color_space == JCS_YCCK || cinfo.jpeg_color_space == JCS_GRAYSCALE) {
+        if (cinfo.jpeg_color_space == JCS_CMYK || cinfo.jpeg_color_space == JCS_YCCK) {
             jpeg_destroy_decompress(&cinfo);
             return IMIO_READERROR;
         }
 
+        cinfo.out_color_space = JCS_RGB;
+
         deleteLoadedProfileData();
         loadedProfileDataJpg = true;
         bool hasprofile = read_icc_profile (&cinfo, (JOCTET**)&loadedProfileData, (unsigned int*)&loadedProfileLength);
@@ -677,8 +679,8 @@ int ImageIO::getTIFFSampleFormat (Glib::ustring fname, IIOSampleFormat &sFormat,
 
     TIFFClose(in);
 
-    if (photometric == PHOTOMETRIC_RGB) {
-        if ((samplesperpixel == 3 || samplesperpixel == 4) && sampleformat == SAMPLEFORMAT_UINT) {
+    if (photometric == PHOTOMETRIC_RGB || photometric == PHOTOMETRIC_MINISBLACK) {
+        if ((samplesperpixel == 1 || samplesperpixel == 3 || samplesperpixel == 4) && sampleformat == SAMPLEFORMAT_UINT) {
             if (bitspersample == 8) {
                 sFormat = IIOSF_UNSIGNED_CHAR;
                 return IMIO_SUCCESS;
@@ -820,7 +822,7 @@ int ImageIO::loadTIFF (Glib::ustring fname)
     allocate (width, height);
 
     float minValue[3] = {0.f, 0.f, 0.f}, maxValue[3] = {0.f, 0.f, 0.f};
-    unsigned char* linebuffer = new unsigned char[TIFFScanlineSize(in)];
+    unsigned char* linebuffer = new unsigned char[TIFFScanlineSize(in) * (samplesperpixel == 1 ? 3 : 1)];
 
     for (int row = 0; row < height; row++) {
         if (TIFFReadScanline(in, linebuffer, row, 0) < 0) {
@@ -829,10 +831,21 @@ int ImageIO::loadTIFF (Glib::ustring fname)
             return IMIO_READERROR;
         }
 
-        if (samplesperpixel > 3)
+        if (samplesperpixel > 3) {
             for (int i = 0; i < width; i++) {
                 memcpy (linebuffer + i * 3 * bitspersample / 8, linebuffer + i * samplesperpixel * bitspersample / 8, 3 * bitspersample / 8);
             }
+        }
+        else if (samplesperpixel == 1) {
+            const size_t bytes = bitspersample / 8;
+            for (int i = width - 1; i >= 0; --i) {
+                const unsigned char* const src = linebuffer + i * bytes;
+                unsigned char* const dest = linebuffer + i * 3 * bytes;
+                memcpy(dest + 2 * bytes, src, bytes);
+                memcpy(dest + 1 * bytes, src, bytes);
+                memcpy(dest + 0 * bytes, src, bytes);
+            }
+        }
 
         if (sampleFormat & (IIOSF_LOGLUV24 | IIOSF_LOGLUV32 | IIOSF_FLOAT)) {
             setScanline (row, linebuffer, bitspersample, minValue, maxValue);
diff --git a/rtengine/iplab2rgb.cc b/rtengine/iplab2rgb.cc
index 6b04bb8f2..218dbf6fe 100644
--- a/rtengine/iplab2rgb.cc
+++ b/rtengine/iplab2rgb.cc
@@ -169,9 +169,7 @@ Image8* ImProcFunctions::lab2rgb (LabImage* lab, int cx, int cy, int cw, int ch,
         cmsUInt32Number flags = cmsFLAGS_NOOPTIMIZE | cmsFLAGS_NOCACHE;
         if (icm.outputBPC) {
             flags |= cmsFLAGS_BLACKPOINTCOMPENSATION;
-            printf("lab2rgb / bpc=true\n");
         }
-        else printf("lab2rgb / bpc=false\n");
         lcmsMutex->lock ();
         cmsHPROFILE LabIProf  = cmsCreateLab4Profile(nullptr);
         cmsHTRANSFORM hTransform = cmsCreateTransform (LabIProf, TYPE_Lab_DBL, oprofG, TYPE_RGB_8, icm.outputIntent, flags);  // NOCACHE is important for thread safety
@@ -290,19 +288,15 @@ Image16* ImProcFunctions::lab2rgb16 (LabImage* lab, int cx, int cy, int cw, int
         iccStore->getGammaArray(icm, *ga);
         oprof = iccStore->createGammaProfile(icm, *ga);
         lcmsMutex->unlock ();
-        printf("iccStore->createGammaProfile(icm, *ga);\n");
     } else {
         oprof = iccStore->getProfile (icm.output);
-//        printf("iccStore->getProfile (%s);\n", icm.output.c_str());
     }
 
     if (oprof) {
         cmsUInt32Number flags = cmsFLAGS_NOOPTIMIZE | cmsFLAGS_NOCACHE;
         if (icm.outputBPC) {
             flags |= cmsFLAGS_BLACKPOINTCOMPENSATION;
-//            printf("lab2rgb16 / icm.outputBPC=true / outputIntent=%d\n", icm.outputIntent);
         }
-//        else printf("lab2rgb16 / icm.outputBPC=false / outputIntent=%d\n", icm.outputIntent);
         lcmsMutex->lock ();
         cmsHPROFILE iprof = cmsCreateLab4Profile(nullptr);
         cmsHTRANSFORM hTransform = cmsCreateTransform (iprof, TYPE_Lab_FLT, oprof, TYPE_RGB_16, icm.outputIntent, flags);
diff --git a/rtgui/guiutils.h b/rtgui/guiutils.h
index 87213dc04..722b706eb 100644
--- a/rtgui/guiutils.h
+++ b/rtgui/guiutils.h
@@ -526,7 +526,7 @@ public:
     // you have to check if the surface is created thanks to surfaceCreated before starting to draw on it
     bool surfaceCreated()
     {
-        return surface;
+        return static_cast<bool>(surface);
     }
     Cairo::RefPtr<Cairo::ImageSurface> getSurface()
     {