diff --git a/tools/cmd/icat/native.go b/tools/cmd/icat/native.go
index 93909b518..489ce0ffe 100644
--- a/tools/cmd/icat/native.go
+++ b/tools/cmd/icat/native.go
@@ -13,7 +13,7 @@ import (
 
 var _ = fmt.Print
 
-func add_frame(imgd *image_data, img image.Image) {
+func add_frame(imgd *image_data, img image.Image, is_opaque bool) {
 	if flip {
 		img = imaging.FlipV(img)
 	}
@@ -23,33 +23,48 @@ func add_frame(imgd *image_data, img image.Image) {
 	b := img.Bounds()
 	f := image_frame{width: b.Dx(), height: b.Dy()}
 	dest_rect := image.Rect(0, 0, f.width, f.height)
-	var rgba *image.NRGBA
-	m, err := shm.CreateTemp("icat-*", uint64(f.width*f.height*4))
-	if err != nil {
-		rgba = image.NewNRGBA(dest_rect)
-	} else {
-		rgba = &image.NRGBA{
-			Pix:    m.Slice(),
-			Stride: 4 * f.width,
-			Rect:   dest_rect,
+	var final_img image.Image
+
+	if is_opaque || remove_alpha != nil {
+		var rgb *images.NRGB
+		m, err := shm.CreateTemp("icat-*", uint64(f.width*f.height*3))
+		if err != nil {
+			rgb = images.NewNRGB(dest_rect)
+		} else {
+			rgb = &images.NRGB{Pix: m.Slice(), Stride: 3 * f.width, Rect: dest_rect}
+			f.shm = m
 		}
-		f.shm = m
+		imgd.format_uppercase = "RGB"
+		f.in_memory_bytes = rgb.Pix
+		final_img = rgb
+	} else {
+		var rgba *image.NRGBA
+		m, err := shm.CreateTemp("icat-*", uint64(f.width*f.height*4))
+		if err != nil {
+			rgba = image.NewNRGBA(dest_rect)
+		} else {
+			rgba = &image.NRGBA{Pix: m.Slice(), Stride: 4 * f.width, Rect: dest_rect}
+			f.shm = m
+		}
+		imgd.format_uppercase = "RGBA"
+		f.in_memory_bytes = rgba.Pix
+		final_img = rgba
 	}
-	images.PasteCenter(rgba, img, remove_alpha)
-	imgd.format_uppercase = "RGBA"
-	f.in_memory_bytes = rgba.Pix
+	images.PasteCenter(final_img, img, remove_alpha)
 	imgd.frames = append(imgd.frames, &f)
 }
 
-func load_one_frame_image(imgd *image_data, src *opened_input) (image.Image, error) {
-	img, err := imaging.Decode(src.file, imaging.AutoOrientation(true))
+func load_one_frame_image(imgd *image_data, src *opened_input) (img image.Image, is_opaque bool, err error) {
+	img, err = imaging.Decode(src.file, imaging.AutoOrientation(true))
 	src.Rewind()
-	if err == nil {
-		// reset the sizes as we read EXIF tags here which could have rotated the image
-		imgd.canvas_width = img.Bounds().Dx()
-		imgd.canvas_height = img.Bounds().Dy()
-		set_basic_metadata(imgd)
+	if err != nil {
+		return
 	}
+	// reset the sizes as we read EXIF tags here which could have rotated the image
+	imgd.canvas_width = img.Bounds().Dx()
+	imgd.canvas_height = img.Bounds().Dy()
+	set_basic_metadata(imgd)
+	is_opaque = images.IsOpaque(img)
 	if imgd.needs_scaling {
 		if imgd.canvas_width < imgd.available_width && opts.ScaleUp && place != nil {
 			r := float64(imgd.available_width) / float64(imgd.canvas_width)
@@ -59,7 +74,7 @@ func load_one_frame_image(imgd *image_data, src *opened_input) (image.Image, err
 		img = imaging.Resize(img, imgd.canvas_width, imgd.canvas_height, imaging.Lanczos)
 		imgd.needs_scaling = false
 	}
-	return img, err
+	return
 }
 
 func render_image_with_go(imgd *image_data, src *opened_input) (err error) {
@@ -67,11 +82,11 @@ func render_image_with_go(imgd *image_data, src *opened_input) (err error) {
 	case "GIF":
 		return fmt.Errorf("TODO: implement GIF decoding")
 	default:
-		img, err := load_one_frame_image(imgd, src)
+		img, is_opaque, err := load_one_frame_image(imgd, src)
 		if err != nil {
 			return err
 		}
-		add_frame(imgd, img)
+		add_frame(imgd, img, is_opaque)
 	}
 	return nil
 }
diff --git a/tools/utils/images/opaque.go b/tools/utils/images/opaque.go
index c81c7db02..e1187fdd2 100644
--- a/tools/utils/images/opaque.go
+++ b/tools/utils/images/opaque.go
@@ -33,6 +33,8 @@ func IsOpaque(img image.Image) bool {
 		return img.(*image.Paletted).Opaque()
 	case *image.Uniform:
 		return img.(*image.Uniform).Opaque()
+	case *image.YCbCr:
+		return img.(*image.YCbCr).Opaque()
 	case *NRGB:
 		return img.(*NRGB).Opaque()
 	}
diff --git a/tools/utils/images/to_rgb.go b/tools/utils/images/to_rgb.go
index 3294abbfd..3a12eaf16 100644
--- a/tools/utils/images/to_rgb.go
+++ b/tools/utils/images/to_rgb.go
@@ -399,7 +399,7 @@ func (s *scanner_rgb) scan(x1, y1, x2, y2 int, dst []uint8) {
 	}
 }
 
-func paste_nrgb_onto_opaque(background *image.NRGBA, img image.Image, pos image.Point, bgcol *NRGBColor) {
+func paste_nrgb_onto_opaque(background *NRGB, img image.Image, pos image.Point, bgcol *NRGBColor) {
 	bg := NRGBColor{}
 	if bgcol != nil {
 		bg = *bgcol
@@ -408,3 +408,11 @@ func paste_nrgb_onto_opaque(background *image.NRGBA, img image.Image, pos image.
 	src := newScannerRGB(img, bg)
 	run_paste(src, background, pos, func(dst []byte) {})
 }
+
+func NewNRGB(r image.Rectangle) *NRGB {
+	return &NRGB{
+		Pix:    make([]uint8, 3*r.Dx()*r.Dy()),
+		Stride: 3 * r.Dx(),
+		Rect:   r,
+	}
+}
diff --git a/tools/utils/images/to_rgba.go b/tools/utils/images/to_rgba.go
index 82414056c..42f825772 100644
--- a/tools/utils/images/to_rgba.go
+++ b/tools/utils/images/to_rgba.go
@@ -330,7 +330,7 @@ type Scanner interface {
 	bounds() image.Rectangle
 }
 
-func run_paste(src Scanner, background *image.NRGBA, pos image.Point, postprocess func([]byte)) {
+func run_paste(src Scanner, background image.Image, pos image.Point, postprocess func([]byte)) {
 	pos = pos.Sub(background.Bounds().Min)
 	pasteRect := image.Rectangle{Min: pos, Max: pos.Add(src.bounds().Size())}
 	interRect := pasteRect.Intersect(background.Bounds())
@@ -338,15 +338,29 @@ func run_paste(src Scanner, background *image.NRGBA, pos image.Point, postproces
 		return
 	}
 	bytes_per_pixel := src.bytes_per_pixel()
+	var stride int
+	var pix []uint8
+	switch v := background.(type) {
+	case *image.NRGBA:
+		i := background.(*image.NRGBA)
+		stride = i.Stride
+		pix = i.Pix
+	case *NRGB:
+		i := background.(*NRGB)
+		stride = i.Stride
+		pix = i.Pix
+	default:
+		panic(fmt.Sprintf("Unsupported image type: %v", v))
+	}
 	parallel(interRect.Min.Y, interRect.Max.Y, func(ys <-chan int) {
 		for y := range ys {
 			x1 := interRect.Min.X - pasteRect.Min.X
 			x2 := interRect.Max.X - pasteRect.Min.X
 			y1 := y - pasteRect.Min.Y
 			y2 := y1 + 1
-			i1 := y*background.Stride + interRect.Min.X*bytes_per_pixel
+			i1 := y*stride + interRect.Min.X*bytes_per_pixel
 			i2 := i1 + interRect.Dx()*bytes_per_pixel
-			dst := background.Pix[i1:i2]
+			dst := pix[i1:i2]
 			src.scan(x1, y1, x2, y2, dst)
 			postprocess(dst)
 		}
@@ -381,7 +395,7 @@ func Paste(background image.Image, img image.Image, pos image.Point, opaque_bg *
 	case *image.NRGBA:
 		paste_nrgba_onto_opaque(background.(*image.NRGBA), img, pos, opaque_bg)
 	case *NRGB:
-		paste_nrgb_onto_opaque(background.(*image.NRGBA), img, pos, opaque_bg)
+		paste_nrgb_onto_opaque(background.(*NRGB), img, pos, opaque_bg)
 	default:
 		panic("Unsupported background image type")
 	}