PDFcover quality and internal colour photos in Greyscale

[Mark Knight]

hi there, i have 2 queries....


1) my pdf is good quality, but on the url lulu give me it looks poor.
www.lulu.com/content/paperback-book/wayki-wayki/7877796

is this just to cache so the page runs fast or has my pdf been downgraded?


2) i have lots of colour photos n diagrams but wish to print in black n white.......i was told this is bad as it is black ON or black OFF only. anyone know anything about this? Createspace book creation site claim to do proper greyscale do they not?

thx

[Belinda D'Alessandro]

1) The preview will always look different from what the printed version because of the way the preview is generated. The only true way to see how your document will look when it prints is to get a printed copy.

2) You can choose either colour or black and white. If you choose to print in black and white but upload a colour interior, the interior will print in black and white, not colour. The process is exactly the same at both Lulu and CreateSpace and neither of them make any changes to your PDF. The print you get from Lulu may look different from the print you get from CreateSpace, but only because they use different printing machines.

Colour images can print alright if you choose black and white but do not necessarily render well. It all depends on the quality of the images. Again, the only true way to see how your document will look when it prints is to get a printed copy. If you're not happy with the way the document prints colour images in black and white, then you'll need to make adjustments to the images yourself.

[ulillillia]

1. Previews are based on 100 dpi for download speed and bandwidth reasons. The actual print copy is unaffected.

2. I have plenty of color images myself, though I used a special brightness-matching conversion algorithm to convert the color images to grayscale. This enhances the contrast and quality. I developed it through doing experiments on my own printer.

[Kevin Lomas]

the preview can be a worry. One example of mine is red text on blue (front cover) and although the printed proof looks great, in the preview the red 'smudges' in to the blue and looks a mess. There is no real excuse for it now because a compressed jpg is tiny and that is what DLs (if they use jpgs for the previews that is) so you can view it. I used to have a site with art on and some of the files decrompressed where 20mb and they loaded just fine. There is no reason the previews cannot be 300dpi. (They are huge now anyway! why not make them smaller?) I think all it is, is the lulu's servers are old and slow.

[ulillillia]

When saving as JPG, I found out how to get rid of the smudging effect - use the "1x1, 1x1, 1x1" subsampling instead of the default "2x1, 1x1, 1x1". It increases the file size some, but a slight decrease in the quality will offset this. I've done tests so I know. Compare these 3 images and you'll know what I mean:


Control (PNG) - 68,951 bytes (as a PNG)


2x1 quality 90 - 43,700 bytes


2x1 quality 60 - 20,927 bytes


1x1 quality 90 - 57,920 bytes


1x1 quality 60 - 26,811 bytes.

The 1x1 with quality 60 looks about as good as the 2x1 with quality 90 and has a much smaller file size (61 1/3% as big). Notice how much more crisp the emerald is in the fifth image compared to that of the second? The image is also closer to the original in terms of brightness (notice how the blue spring seems to have been darkened in the second and third images). Perhaps something like this should be used with the previews. I find the 100 dpi resolution sufficient enough for a preview (as long as the text can be read, you should be fine). 300 dpi would, theoretically, need 9 times the disk space. Perhaps this could be a good pointer to help your old server out.

[Kevin Lomas]

my jpegs are not smudged, the Preview lulu generates is. As to all those examples, they all look ths same on here and I have no idea what you are talking about to be honest I use PSP 5 and it has a sliding bar for compression and I always leave it on Low.