17th September 2003, 10:17 PM
Agfa digital lab causes artefacting?
I just got a stack of prints back from our local Agfa lab, and notice a problem that I'd also seen before on a few prints I'd got done with them.
Let me first make the mention this is NOT the usual low-res jaggies or jpeg artefacts. I've been working in both print and video graphics for 10 years now and this is different.
I got a bunch of prints done at instant photo kiosks in Japan and none of them had this problem.
Firstly there was a lot of weird aliasing artefacting on diagonals, especially between high contrast areas. This was a bit unusual as it seems rough and uneven. It's not the same every step. It looks like when you enlarge in photoshop to a size other than a multiple, without using bicubic resampling.
Second, there it looked like the image was converted into uniform blocks in certain areas. This did not look like the usual jpeg dirty compression.
These prints were in 1024x683 or 1600x1068 res. Now remember that I printed these and they looked GREAT from an instant kiosk.. but from the photo lab look whacked. In fact, my lo-res 640x427 shots actually came out better at the lab than my higher res ones.
Also, do these labs enlarge before printing? I supplied my images at 15cm x 10cm.. the correct aspect, but it looks like they've been enlarged and then cropped by at least 0.5cm all around! Is this a normal procedure? I read a mention somewhere about over-sharpening? Is this a possible cause? However, even if I don't adjust my images at all, they still come out whacked
Last, when I look at the prints with my lupe, the Agfa one is made of dots. These dots are arranged in a uniform grid with slight white space between. I thought photos were meant to be continous tone? When I look at the ones from the instant kiosk they are continuous tone! No dots to be seen at all.
Well, if anyone can offer any assistance I'd greatly appreciate it. I'm not really happy with the results. Thanks.
18th September 2003, 12:18 PM
I followed this up with another lab using the same system. My conclusion is that the D-Lab is crap and I need to find somewhere with a dedicated dye-sub system.
18th September 2003, 01:41 PM
Which local Agfa digital lab are u referring to?
I only know of HotPrint@China Square which gives excellent results everytime I process my prints there. It would be best if you could show samples of what you are trying to illustrate. Without actually seeing the actual prints it is close to impossible to tell what could and have went wrong.
Did you talk to the Agfa lab regarding the problematic prints?
18th September 2003, 02:23 PM
Yeah I had a big chat with the guy there, but no luck. It seems the Agfa system uses a LCD to expose the image onto the film. When it does this it also enlarges the print slightly. You can't stop it enlarging. I suspect the res of my was conflicting with something during the enlarging, and causing interpolation problems which were then going on to make the weird aliasing effect.
It all makes me wonder a bit. How much of a hope has the novice digital camera user got of framing their shots? If most cameras are 4:3, you'll loose a good cm top and bottom.. then the processing chops off another 0.5cm all around. It's a bit of a problem. I can allow for this, but I still wont be able to solve the jaggies problem unless I can find a dye-sub lab.
I'll try to get some scans of the prob and upload them.