diff --git a/reader.lua b/reader.lua
index 2866025f7..139a2c4a7 100755
--- a/reader.lua
+++ b/reader.lua
@@ -51,6 +51,7 @@ rcount = 5
 rcountmax = 5
 
 globalzoom = -1
+globalgamma = -1.0
 
 if optarg["d"] == "k3" then
 	-- for now, the only difference is the additional input device
@@ -66,6 +67,10 @@ else
 	input.open("/dev/input/event1")
 end
 
+if optarg["G"] ~= nil then
+	globalgamma = optarg["G"]
+end
+
 doc = pdf.openDocument(ARGV[optind], optarg["p"] or "")
 
 print("pdf has "..doc:getPages().." pages.")
@@ -73,12 +78,11 @@ print("pdf has "..doc:getPages().." pages.")
 fb = einkfb.open("/dev/fb0")
 width, height = fb:getSize()
 
-init_tilecache()
-
 nulldc = pdf.newDC()
 
-function setzoom(cacheslot)
-	local pwidth, pheight = cache[cacheslot].page:getSize(nulldc)
+function setzoom(page, cacheslot)
+	local dc = pdf.newDC()
+	local pwidth, pheight = page:getSize(nulldc)
 
 	-- default zoom: fit to page
 	local zoom = width / pwidth
@@ -90,18 +94,19 @@ function setzoom(cacheslot)
 		offset_y = 0
 	end
 
-	cache[cacheslot].dc:setZoom(zoom)
-	cache[cacheslot].dc:setOffset(offset_x, offset_y)
+	dc:setZoom(zoom)
+	dc:setOffset(offset_x, offset_y)
 
 	-- set gamma here, we don't have any other good place for this right now:
-	if optarg["G"] then
-		print("gamma correction: "..optarg["G"])
-		cache[cacheslot].dc:setGamma(optarg["G"])
+	if globalgamma ~= -1.0 then
+		print("gamma correction: "..globalgamma)
+		dc:setGamma(globalgamma)
 	end
+	return dc
 end
 
 function show(no)
-	local slot = draworcache(no)
+	local slot = draworcache(no,globalzoom,0,0,width,height,globalgamma)
 	fb:blitFullFrom(cache[slot].bb)
 	if rcount == rcountmax then
 		print("full refresh")
@@ -123,22 +128,18 @@ function goto(no)
 	show(no)
 	if no < doc:getPages() then
 		-- always pre-cache next page
-		draworcache(no+1)
+		draworcache(no+1,globalzoom,0,0,width,height,globalgamma)
 	end
 end
 
 function modify_gamma(offset)
-	local slot = slot_visible
-	local gamma = cache[slot].dc:getGamma();
-	if gamma == -1 then
-		gamma = 1
+	if globalgamma == -1 then
+		globalgamma = 1
 	end
-	local no = cache[slot].no
-	print("modify_gamma "..no.." slot="..slot.." gamma="..gamma.." offset="..offset)
-	gamma = gamma + offset;
-	optarg["G"] = gamma; -- for next page
-	freecache()
-	goto(no)
+	print("modify_gamma, gamma="..globalgamma.." offset="..offset)
+	globalgamma = globalgamma + offset;
+	clearcache()
+	goto(pageno)
 end
 
 function mainloop()
@@ -147,13 +148,9 @@ function mainloop()
 		if ev.type == EV_KEY and ev.value == EVENT_VALUE_KEY_PRESS then
 			local secs, usecs = util.gettime()
 			if ev.code == KEY_PAGEUP then
-				print(cache)
 				goto(pageno + 1)
-				print(cache)
 			elseif ev.code == KEY_PAGEDOWN then
-				print(cache)
 				goto(pageno - 1)
-				print(cache)
 			elseif ev.code == KEY_BACK then
 				return
 			elseif ev.code == KEY_UP then
diff --git a/tilecache.lua b/tilecache.lua
index 31c9e1040..8aa7657a3 100755
--- a/tilecache.lua
+++ b/tilecache.lua
@@ -1,64 +1,51 @@
 --[[
 a cache for rendered tiles
 ]]--
-
-function init_tilecache()
-	cache = {
-		{ age = 0, no = 0, bb = blitbuffer.new(width, height), dc = pdf.newDC(), page = nil },
-		{ age = 0, no = 0, bb = blitbuffer.new(width, height), dc = pdf.newDC(), page = nil },
-		{ age = 0, no = 0, bb = blitbuffer.new(width, height), dc = pdf.newDC(), page = nil }
-	}
-end
-function freecache()
-	for i = 1, #cache do
-		if cache[i].page ~= nil then
-			print("freeing slot="..i.." oldpage="..cache[i].no)
-			cache[i].page:close()
-			cache[i].page = nil
-		end
-	end
-end
-function checkcache(no)
-	for i = 1, #cache do
-		if cache[i].no == no and cache[i].page ~= nil then
-			print("cache hit: slot="..i.." page="..no)
-			return i
-		end
+cache_max_memsize = 1024*1024*5 -- 5MB tile cache
+cache_current_memsize = 0
+cache = {}
+cache_max_age = 20
+function cacheclaim(size)
+	if(size > cache_max_memsize) then
+		error("too much memory claimed")
+		return false
 	end
-	print("cache miss")
-	return nil
-end
-function cacheslot()
-	freeslot = nil
-	while freeslot == nil do
-		for i = 1, #cache do
-			if cache[i].age > 0 then
-				print("aging slot="..i)
-				cache[i].age = cache[i].age - 1
+	repeat
+		for k, v in pairs(cache) do
+			if v.age > 0 then
+				print("aging slot="..k)
+				v.age = v.age - 1
 			else
-				if cache[i].page ~= nil then
-					print("freeing slot="..i.." oldpage="..cache[i].no)
-					cache[i].page:close()
-					cache[i].page = nil
-				end
-				freeslot = i
+				cache_current_memsize = cache_current_memsize - v.size
+				cache[k] = nil
+				break -- out of for loop
 			end
 		end
-	end
-	print("returning free slot="..freeslot)
-	return freeslot
+	until cache_current_memsize + size <= cache_max_memsize
+	cache_current_memsize = cache_current_memsize + size
+	print("cleaned cache to fit new tile (size="..size..")")
+	return true
 end
-
-function draworcache(no)
-	local slot = checkcache(no)
-	if slot == nil then
-		slot = cacheslot()
-		cache[slot].no = no
-		cache[slot].age = #cache
-		cache[slot].page = doc:openPage(no)
-		setzoom(slot)
-		print("drawing page="..no.." to slot="..slot)
-		cache[slot].page:draw(cache[slot].dc, cache[slot].bb, 0, 0)
+function draworcache(no, zoom, offset_x, offset_y, width, height, gamma)
+	local hash = cachehash(no, zoom, offset_x, offset_y, width, height, gamma)
+	if cache[hash] == nil then
+		cacheclaim(width * height / 2);
+		cache[hash] = {
+			age = cache_max_age,
+			size = width * height / 2,
+			bb = blitbuffer.new(width, height)
+		}
+		print("drawing page="..no.." to slot="..hash)
+		local page = doc:openPage(no)
+		local dc = setzoom(page, hash)
+		page:draw(dc, cache[hash].bb, 0, 0)
+		page:close()
 	end
-	return slot
+	return hash
+end
+function cachehash(no, zoom, offset_x, offset_y, width, height, gamma)
+	return no..'_'..zoom..'_'..offset_x..','..offset_y..'-'..width..'x'..height..'_'..gamma;
+end
+function clearcache()
+	cache = {}
 end