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 Post subject: Resolution
PostPosted: Sat Apr 30, 2005 11:24 pm 
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Dear Andrea,

I am glad that a friend of mine called my attention to your programme!
It is great that you offer it for free.

Just a few questions in regards to the resolution:
If I understand it correctly the resolution of the final mosaic is unlimited. We are planning to create a mosaic in poster format (60x80 or 70x100cm) as a wedding gift for a very good friend. I wonder how large the resolution of the picture that should be created as a mosaic has to be. As far as I know a 6 megapixel camera for instance is only sufficient for A3 prints (40x30cm), but we are looking at four times the size or even more. Does that mean that the main picture should be a scan of a conventional photo with a resolution of 20-30 or more megapixels even though it would be printed as a mosaic?
How large should the resolution for the little pictures be? Is there a limit for the resolution of the mosaic pieces? I guess we would use 50x30 pieces (print with 300-600 dpi?) but unfortunately will probably only have 200-300 pictures.

Thank you very much in advance
Kind regards

Klaus


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 Post subject: Re: Resolution
PostPosted: Sun May 01, 2005 3:29 am 
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Hello Klaus,

the resolution of the tiles depend on how big they will be in the final print. If for example every tile will have a width of 1 inch or less (2.54 cm) then a width of 300 pixels means you have a 300 DPI image quality.

This is more than enough also because the printing DPI is always lower than a image DPI. What I want to say is that the printer companies claim for a 600 DPI that in reality have a lower resolution. In any case 300 DPI is enough for most cases. I don't suggest that the tiles have a high resolution, to not go over 1000 pixels of widht. In my database of 20.000 nature photos the average image have a size of 150 to 300 pixels.

For the final produced mosaic in A0 size (70x100 cm) we can make the same assumption. 100 cm = 40 inch. So for a 300 DPI print I need a width of 300x40 = 12000 pixels. Just be careful to not grow too much with the final size because the program use much memory.

For the original image to use as the mosaic template any resolution is ok. Even very tiny images.

byee
andrea


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PostPosted: Sun May 01, 2005 6:57 pm 
Hi Andrea,

Thank you for your quick response! Do I understand you correctly that the main image (so not the final result, but the one photo, which is used as the template) does not need to have a very high resolution? As I said, because of the 75x100cm poster size that we are thinking of, I was wondering if the template needs a resolution of 20 or more megapixels. You say that even a low resolution would be sufficient for that. Is there a minimum resolution for the template?
If we choose 75x100cm (30x40inch) for the poster size, with a resolution for the print of 300dpi, then the poster would be 9,000x12,000 pixels=108 megapixels. In a photo shop in Sydney I was told that for a normal poster print of this size 300dpi would be sufficient. However, as people also look from an unusually close distance at mosaic posters, to see the details of the little photos, I wonder if 600dpi would be better. I was told that they don't charge more for 600dpi. But with 600dpi the final result would have 432 megapixels and I wonder how my computer (pentium 4 1.8, 256DDR RAM) would cope with that. Can you give me an idea how long about it takes such a PC to process the mosaic. On your website I read about a huge mosaic (I think the width was 3 metres) which took 96 hours to be processed.
Last question: Is jpg alright or should we save the mosaic in a different format?

Thank you very much in advance!
Ciao

Klaus


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PostPosted: Mon May 02, 2005 2:06 am 
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Yes, the main image don't need a high resolution, a width of 300 pixels is already enough. 1 Megapixel is enough.

I suggest you to make several mosaics with the standard width of 3500 pixels. Then only when you are ready for the final image use a higher resolution. You have a fast computer but unfortunately a low amount of memory and it can take some time to generate the image. Basically it depend on the number of tiles and the number of images in your database. On my computer a 1000 tiles mosaic with a database of 20000 nature photos take some minutes to complete at 3500 pixels.

AndreaMosaic actually read only JPG images.

byeee
andrea


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