Blurry Cover in Preview (png upload) One Piece Cover

I uploaded a png file for my one piece cover after making it in GIMP.  It looks really distorted or blurry in the preview, and even a little on the thumbnail on my author page.  The png I uploaded was 72dpi, so I opened this file in GIMP and put the image setting to 300dpi and re-uploaded.  It stil has the same amount of distortion.  In both cases the cover PDF file that lulu generates lookds ok.  What's going on?  Am I going to have to set GIMP to 300dpi before I begin the design?  A lot of the distortion is just around text on simple, colored backgrounds.  Or am I going to have to convert the PDF and then load that file to lulu? 

 

https://www.lulu.com/shop/thomas-smyth/of-woodbridge-and-hedgely/paperback/product-22108541.html

 

Thanks,

 

Andrew Fez

Comments

  • Your cover image needs to be both 300dpi *and* sufficiently large to cover your book format - 15.25cm wide and 22.86cm tall (six by nine inches). That needs an original image size of 1,800 by 2,700 pixels.

     

    Scale your original high resolution image to that size, set the resolution to 300dpi, and try again. I suspect that when yo have changed the resolution, you have not changed the size, so it's still the same pixels which are being stretched in the print.

     

    Neil

  • Just KevinJust Kevin Lulu Genius

    You cannot just change a low DPI to a high DPI successfully because it's still the same low res image you are trying to tell to be high-res. Hence the distortion etc. It's not bad if you go from say 250 to 300 because it's not a great change. Basically what I am saying is it will just have the effect of enlarging the pixels to the effect that it could end up looking like Lego. Granted each brick will be made up of a lot of pixels, but that brickiness is not the effect you want.

     

    Bitmap images are, with a few

     

    BTW. The Previews on the Spotlights are lo-res flash, and there's nothing can be done about that.

     

    PS. The software that comes with some scanners can extrapolate, which means it uses some algorythm to enlarge things and fill in the extra pixels rather that just increasing the existing ones. Something like that anyway. That's one way of creating high res from lo res.

     

    http://en.wikipedia.org/wiki/Extrapolation

     

     

  • Thanks Neil,

     

    I double checked it:  It's 3863 x 2775, just like the one piece cover page asks for.  I even went back to GIMP, rendered the original file i used to create the cover to 300dpi, to avoid just blowing up the 72dpi image (and thusly not getting the true resolution).  When I get some time here in a week, perhaps I'll set GIMP to 300 before I start, and then just recreate the cover to see if that makes any difference. 

     

    It's funny, because the print-ready PDF it generates is fine.  I imagine the actual print will look ok; it's just the preview is discouraging. 

     

    See ya,

     

    Andrew Fez

  • Just KevinJust Kevin Lulu Genius

    My large posting is invisible then?

     

    So you do mean the Preview on the Spotlights then? Because they are lo-res.

  • Thanks Kevin,

     

    Yeah, it's the Spotlight Preview that is distorted.  But mine seems more distored and jagged compared to the other book previews on Lulu.  I'm guessing it's because the image I used inside my cover is at a different dpi than the rest of the cover and the Preview is trying to conform to that, distorting everything else.  I did re-render my image file to 300dpi, but it didn't clear it up. 

  • Just KevinJust Kevin Lulu Genius

    You could try updating Flash, but if you say other peoples' Previews look better that may not improve things.

     

    Inside your cover? Sorry I thought you meant just the actual cover. There's the possibility that the PR PDF for the cover is not the same resolution as the one for the pages, because usually there's no need for it to be.

     

    I still maintain it's not possible simply to change the DPI of an image because it's still working from the original DPI. I have even tried it by creating a blank high-res image and pasting a lo-res one in to it. You have to expand it also but it will just end up blocky if there's too great a difference in the DPI.

     

    It can take some time but it does work as I suggested using the clever software in a scanner. I scanned some postcard sized photos with the scanner set at 9,000dpi (!) and it managed to blow them up massive with no loss of detail (and old photos are very lo-res, often as low as 17 dpi) then I reduced them to fit A4 pages, again with no loss. Even if one has to first print out the original images to scan them it's always worth a try.

     

    I assume you are viewing on a PC? One never knows nowadays!

  • Yeah, Kevin - it's a fundamental of any digital sampling system that you can't put in what isn't there to start with. If your original image is six inches across at 75dpi, you have only 450 pixels across the page.

     

    You can interpolate between the pixels, and some of the algorithms are now both good and fast, but you won't increase the resolution and at best you will have an image with the same number of 'pixel equivalences' nicely blurred into each other.

     

    The best bet is always to take the highest resolution image you can get and scale *down* from there to match the output format you need.

     

    I'm no Gimp or Photoshop expert, but I would expect both of them to leave the image pixels unchanged when you try and change the dpi value - which is after all just a parameter in the metadata describing the image. It will only change the size at which the image should be printed out, not insert or remove pixels. So if you have a 75dpi image and tell it it's really 300dpi, it will only be a quarter of the size when printed.

     

    Neil

     

    p.s. if your vintage photos are only 17dpi effective resolution, they weren't well done: old film emulsions weren't the sharpest in the world but a large negative, and often a contact print, gives *stunning* resolution. I scan 4"x5" negatives at 4800 dpi and still don't hit the grain (but get half-gigapixel images Smiley Happy

  • Just KevinJust Kevin Lulu Genius

    Yeah, Kevin - it's a fundamental of any digital sampling system that you can't put in what isn't there to start with. If your original image is six inches across at 75dpi, you have only 450 pixels across the page.

     

    You can interpolate between the pixels, and some of the algorithms are now both good and fast, but you won't increase the resolution and at best you will have an image with the same number of 'pixel equivalences' nicely blurred into each other.

     

    That's strange because my $500 all-in-one HP printer manages to do it. and the images look the same but larger, although it does also amplify any flaws existing in an image, even paper texture if set too high. It is an advantage if the scanned image is printed using solid colours though rather than any form of dots.

     

    The best bet is always to take the highest resolution image you can get and scale *down* from there to match the output format you need.

     

    Indeed, but that's not always possible. That last things I dealt with were 5.75" x 3.50" photos, some a 100 years old, not in the best of condition..

     

    I'm no Gimp or Photoshop expert, but I would expect both of them to leave the image pixels unchanged when you try and change the dpi value - which is after all just a parameter in the metadata describing the image. It will only change the size at which the image should be printed out, not insert or remove pixels. So if you have a 75dpi image and tell it it's really 300dpi, it will only be a quarter of the size when printed.

     

    What I use, which is Paintshop Pro 5, cannot do that, I am not sure there's any that will change a DPI at the click of an option, or Save As (dpi). One way to almost do it is paste a lo-res in to a new blank hi-res image, then it will be that hi-res, but as you say, still the original size, and increasing the size in any way at all will just expand those original pixels untill they look like bricks. The only way I have managed to do it is that scanning method.

     

    Neil

     

    p.s. if your vintage photos are only 17dpi effective resolution, they weren't well done: old film emulsions weren't the sharpest in the world but a large negative, and often a contact print, gives *stunning* resolution.

     

    Stunning? No one knows what happened to the negitives of mine. They were not all 17dpi though in the days of film, or really even dots, but sort of random 'grains', but depending on the ISO they could be much higher than 17dpi but often needed a longer exposure time.

     

    I scan 4"x5" negatives at 4800 dpi and still don't hit the grain (but get half-gigapixel images :smileyhappy:

     

    If you mean the photos in my traction engine (etc) book, some are 100 years old, some were copied from photos around 50 years ago, some were company postcards handed out by sales reps, some are very old photos of old posters, all are dog-eared and well handled, I had to touch some up, believe me they are not healthy photos. Smiley Happy But at least they are now preserved on my PC.

     

    If you are judging them by Lulu's Previews, don't. They are lo-res Flash thingies. Printed they look OK, or as good as they can be on not-photopaper at  the res PDFs are, printed at whatever res the printers use.

     

    I have a Mrs Beaton's Cookbook from 1909 with amazing adverts in, one day I may turn those in to at least A3 posters ...  Smiley Surprised

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