high resolution large prints : stitching or upsampling ?

[marco_landini]

<p>Hi. I would like to make large prints ( 70x100 cm ; 40x25 inches). The printing lab has a durst lambda 300 dpi printer. I have a nikon d90 12mpixls camera and good primes. I' m not intended to buy a 24 mpxls camera as the d3x, too way out of my budget. So, this is the question : to obtain a large file to be printed to 40x25 inches at 300 dpi, I could take panoramic multi-pictures and stitch them by pano software. But I don't like this way, because of the need of a panoramic tripod head. Even worse, at the end of stitching process, the resulting image will be wrapped anyway , and I hate this effect, expecialy in architectures. The second way is to take one good picture and upsampling it. Photoshop offers bicubic interpolation, and I know there are several enlarging algorithm plugins as genuine fractals. Which way do you suggest me ? Which max enlargement can I obtain by my d90, printed at 300 or 254 dpi without loosing definition and quality, and which enlarging software do you suggest ? Thank you, Marco.</p>

[frank_skomial]

<p>Stitching will allow much greater picture resolution of combined stitched pictures, but it involves careful picture taking and the stitching.</p>

<p>Upsizing, is very easy, and provided by most photo editing software, with varying degree of quality. It can be done easily. Perhaps try to upsize first and see it it meets your picture quality desired standard.<br>

Upsize the picture to the desired large pixel size, and then select small fragment of the large picture, and trint in on a small size paper. Then inspect if the fragment meets your expectation. If not, then try the stitching method. </p>

[patricklavoie]

<p>1_what is the inch size in Photoshop at 300ppi? let say 11x16 @ 300ppi</p>

<p>2_if you put this file at @ 200ppi, you already got a 16x24.. not bad.</p>

<p>3_then you start from this 16x24 @ 200ppi, and by using Photoshop bicubic smoother at 200% you already get a 32x48.. et voila. easy to do, no stiching, no big visual loss of quality.. any photographer can now put there nose on your print ; )</p>

<p>You dont need 300ppi to print, and certainly not at that size. the bigger you print, the lower you can put your ppi because of the viewing distance BUT i like to not go under 200ppi personally.</p>

<p>Photoshop is perfect for the job, you dont need anything else.</p>

[steve_swinehart]

<p>If you're having the file printed on a Durst Lambda, the printer has a built-in upsampling algorithm that is far better than you trying to do it in Photoshop or any other upsampling program.</p>

<p>Just give the lab the file, and the machine will do the rest. Don't try to "help it" by upsampling in Photoshop. The bicubic routines found in PS are the least sophisticated you can use and don't come close to the software in the Lambda, RIP software (inkjet printer), or something as relatively inexpensive as Qimage (inkjet printer).</p>

<p>The best thing you can do is testing - which is as simple as sending file to the lab with a photo that has lot of detail and texture in it. Have them print it at the size you've stated. I prefer to have an entire print made when doing this - some people have only a portion printed to "save money" - but that won't tell you the overall effect of enlarging the image to that size. </p>

<p>Have a full size print made of the entire image so you can hang it on the wall and evalute the print as a whole. Also have a print made at 9.8x13 (or whatever it works out to on an 11x14 print) - that will be a good print with no interpolation. </p>

<p>Then using the smaller print as a basis, look at the enlarged print from a normal viewing distance down to 2-inches from the surface, and then evaluate it with a 5x loupe against the smaller print. That excercise will tell you the difference in image quality. From that point it will be easy for you to decide if the quality of the enlarged image is acceptable or not. If you're really serious about making prints that size, a test print comparison will get you far more relevant information than soliciting opinions on websites.</p>

<p> </p>

[marco_landini]

<p>Thank you guys. @ Steve : if I send my file and let their lambda machine do the upsampling, how have I to prepare the file ? I leave it in the native resolution ( 11x16 at 300 pp) ? And is it better if I do output sharpening for the final size ( 40x25) to my unresized file in photoshop, or is it better not to do any output sharpening ?</p>

[patricklavoie]

<p>have 1 print upsize by them, and make 1.. then compare them both.. and see if the one you make is that *bad*</p>

<p>and they other question is; are you sure they are using a lambda and not a inkjet?</p>

[marco_landini]

<p>yes, it' s a laser durst lambda. It works at 400,300,200,100 ppi. They also have a videolaser polielettronica sublimation printer. It works at 254 ppi and it prints up to 30x20 inches</p>

[gooseberry]

<p>Apparently up-sampling in ACR does a better job than PS, albeit doesn't offer much choice size-wise; for a discussion on that refer <a href="../digital-darkroom-forum/00Xp5J"><em>Up-resing: PS Bicubic Smoother vs. Camera Raw (?)</em></a> thread.<br /> <br />There is one more way of increasing resolution while maintaining the detail (!) Instead of taking different shots and stitching them, you take multiple identical shots and process them for <a href="http://photoacute.com/tech/superresolution_faq.html">super resolution</a> in <a href="http://photoacute.com/studio/index.html">PhotoAcute</a> -- it quadruples my EOS 7D's native pixel dimension of 5184 x 3456 (18MP) to 10404 x 6930 (72MP). Haven't tried that yet, but looks like combining these two techniques should yield > 100MP images, more than enough to print at your target size of 40" @ 300dpi...</p>

[john_houghton]

<p><em>".... at the end of stitching process, the resulting image will be wrapped anyway , and I hate this effect, expecialy in architectures</em>."<br>

If you mean "warped", the stitched image should have the same general appearance as a single shot if the stitching is done correctly. Straight line features such as edges of walls and roof lines should be straighter, since any barrel and pin cushion distortion will be corrected.</p>

 

[steve_swinehart]

 

<blockquote>

<p>Thank you guys. @ Steve : if I send my file and let their lambda machine do the upsampling, how have I to prepare the file ? I leave it in the native resolution ( 11x16 at 300 pp) ? And is it better if I do output sharpening for the final size ( 40x25) to my unresized file in photoshop, or is it better not to do any output sharpening ?</p>

</blockquote>

<p>They probably want it as a TIFF. As for sharpening, the machine has sharpening routines as part of interpolation, but the best thing you can do is call them and discuss the final print with them. The software in the machine has different adjustments that labs will set as they feel gives them the "best" output. Talk with them and ask them how they want the image prepped by you for printing. The machine will have its own profile so you should ask them if they want you to assign the profile (in that case they should send it to you or have it on a website) - or, whether they will assign the profile to the image as part of printing.</p>

<p>Printing is a collaborative process. If you don't give them the chance to collaborate with you on the print and printing process, you won't get the best possible results. I can't stress enough the need to talk with them about the print - most labs I've dealt with love it when a client talks with them, as then there are no misunderstandings or unfulfilled expectations. The print is going to cost you some real $$ at that size, and the lab wants to deliver the best final product they can. The best way they can do that is if you call them, and talk with them before sending the file.</p>

 

[john_houghton]

<p>You might be interested to see this architectural panorama I stitched a while back from 21 images from a Canon 40D + standard 50mm f/1.8 lens (3 rows of 7 portrait images):<br>

<a href="http://www.johnhpanos.com/wimpole2-large.jpg">http://www.johnhpanos.com/wimpole2-large.jpg</a><br>

The image at the above link is a half size copy (5MB). The full size image (15800x6000) prints at 52"x20" at 300ppi. For the stitching, I used PTGui Pro.</p>

 

[marco_landini]

<p>I would try sending the lab a 30x20 file from my d90 at 254 interpolated ppi, for their contone printer.</p>

[marco_landini]

<p>Even if I use a pano head, taking several pictures and stitching them, I will obtain a warped image. It could be not a big issue in landscapes panos, but it will be very unpleasing effect in architectures. As I' m not intended to do large angle view panos , and i' m really intended to take hi resolution pics of subjects as buildings or machinery ( no need to have a circular or arch view) , I need an as flat as possible view, as opposite of pano stitching. What I mean, is I would like to take multi pictures of the subject to create a mosaic NOT rotating the camera around the central axis. Instead I' m thinking about someting as tilt and shift movements. To do this, I could use a tilt-shift lens, but I could only take a couple of pictures to be stitched, no more than 2-4 pictures, as the movements of the tilt-shift lens are very short. To take more ( 6-8) pictures of the same subjects using this technique, keeping costant focal plane, could be usefull to mount the camera on a special head with long vertical and orizzontal brackets or rails, and the camera can move orizontaly (tilting) and verticaly (shifting) on these rails or brackets. You got the idea ?</p>

[john_houghton]

<p>Marco, You don't yet understand. A stitched image looks exactly the same as a single image if it covers the same angle of view and is rendered in rectilinear projection. The individual images will be warped to enable them to align them accurately with each other, but the final image will not have a warped appearance. You only get warped effects when you use cylindrical and equirectangular projections for the stitched image (commonly used for extreme angles of view up to 360 degrees). As you extend the field of view to angles greater than about 100 degrees, then you begin to see increasing stretching effects at the edges in a rectilinear projection. However, this stretching is no worse than you would get with an equivalent standard lens that covered the same view.</p>

[dave_lawson1]

<p>Use good primes (I use a 35mm Nikon prime) and stitch 3 frames. If you get true 200 dpi, for this size of print then you are all set. Viewing ditance for a 40 inch print is 4 to 6 feet away. Don"t get too wrapped up in pixel peeping.</p>