diff --git a/exp/kerokero/prepare_data.py b/exp/kerokero/prepare_data.py
--- a/exp/kerokero/prepare_data.py
+++ b/exp/kerokero/prepare_data.py
@@ -20,7 +20,7 @@ class Sample:
 	SIDE=224
 
 	def __init__(self,img,grid):
-		""":param img: a greyscale image as a 2D np.uint8
+		""":param img: an image as a 3D np.uint8, channels-last
 		:param grid: iterable of 4 EPoints, ie. Corners"""
 		self.img=img
 		self.grid=grid
@@ -38,7 +38,7 @@ class Sample:
 			m=np.matmul(mi,m)
 		m=np.matmul(self._computeCrop(m),m)
 		img=cv.warpPerspective(self.img,m,(self.SIDE,self.SIDE))
-		img=np.float32(img)/255
+		img=cv.cvtColor(img,cv.COLOR_BGR2RGB)
 		grid=Corners(c.transform(m) for c in self.grid)
 		grid=list(map(lambda p: 2*p/self.SIDE-EPoint(1,1), grid))
 		return (img,grid,list(itertools.chain.from_iterable(grid)))
@@ -59,7 +59,7 @@ class Sample:
 		return np.matmul(scale,t2)
 
 	def show(self):
-		img=cv.cvtColor(self.img,cv.COLOR_GRAY2BGR)
+		img=np.copy(self.img)
 		for c in self.grid:
 			cv.circle(img,(int(c.x),int(c.y)),3,[0,255,0],-1)
 		show(img)
@@ -80,15 +80,15 @@ def traverseDirs(root):
 def harvestDir(path):
 	annotations=DataFile(os.path.join(path,"annotations.json.gz"))
 	imgFilter=lambda f: f.is_file() and re.match(r".*\.(jpg|jpeg|png|gif)$", f.name.lower())
-	files=sorted(filter(imgFilter,os.scandir(path)),key=lambda f: f.name)
+	files=sorted(filter(imgFilter,os.scandir(path)),key=lambda f: f.name)[::3]
 	boards=annotations["."]
 	for f in files:
 		img=cv.imread(f.path)
-		img=cv.cvtColor(img,cv.COLOR_BGR2GRAY)
 		for b in boards:
 			sample=Sample(img,b.grid)
+			# sample.show()
 			(transformedImg,transformedGrid,label)=sample.transform()
-			# Sample(np.uint8(transformedImg*255),map(lambda c: (c+EPoint(1,1))*Sample.SIDE/2,transformedGrid)).show()
+			# Sample(transformedImg,map(lambda c: (c+EPoint(1,1))*Sample.SIDE/2,transformedGrid)).show()
 			yield (transformedImg,label)
 
 
@@ -108,8 +108,8 @@ def loadDataset(root):
 	labels=[labels[k] for k in keys]
 	m=int(n*trainRatio)
 	return (
-		(np.float32(images[:m]),np.float32(labels[:m])),
-		(np.float32(images[m:]),np.float32(labels[m:]))
+		(images[:m],np.float32(labels[:m])),
+		(images[m:],np.float32(labels[m:]))
 	)