Rescaling vector graphics (96 dpi > 300 dpi): Is this enough?

[pagelayoutt]

I'm trying to increase the resolution of a series of vector graphics I did several months ago for printing by Lulu (requires sRGB rather than CMYK).

The composite graphics (crossword grids) were designed for onscreen usage, so the overall resolution was left at 96 dpi, but I now realize that my new Affinity Designer (first time usage) has a rescale option. I have increased the dpi from 96 to 300 and maintained RGB/8 (not RGB/16 or RGB/32), I then exported to PNG and PSD (preserve accuracy), but I don't see any visible difference besides a more than doubling in file size. I plan to use Affinity Publisher to incorporate the grids into the final book.

Will the reworked crossword grids be sharp enough for printing?

 

Q--6th draft.psd

[Alfred]

51 minutes ago, pagelayoutt said:

I'm trying to increase the resolution of a series of vector graphics

I’m confused! True vector graphics are resolution independent.

[markw]

I too am a little confused as to why you are exporting the crosswords as PNGs to use and not just using the original vector versions in the book?
As Alfred says, true vector graphics are resolution independent and can be scaled to any size, without loosing visual quality.

The sample PSD file contains a pixel only image, with dpi set to 300, which gives a notional printed size of 4.17” x 4.17” for the crossword, as is, on it’s own.
This may or may not be good enough for your book but we would need more info as to the books printed size and layout.

[pagelayoutt]

Actually, my crossword grids incorporate a variety of graphics for A4 printed pages. The majority are vector graphics, but

(1) I am confused about PNGs, which come in a variety of sizes (does that mean that they will look fuzzy when dpi goes from 96 > 300?

(2) There are also just a few JPGs and even one or two GIFs. In these cases, have used the highest possible resolution to compensate for the inevitable

[markw]

Without getting sucked too deep into the rabbit hole of dpi and raster images (a non vector image, composed of pixels) here;
But the dpi of a digital raster image on it’s own can not be used to describe the quality of the image.
It is just metadata attached to an image, not an inherent property of it.
Unlike the actual number of pixels that make up the image which ultimately is what determines if an image will look good at it’s desired print size.
Insufficient pixels and no matter what dpi you give it, it will look bad.

Your image of the Indian teacher for example is 725px X 1023px.
Printed 4”x6” and it's possible that it will have an insufficient number of pixels to maintain visual quality when viewed close up. And the bigger you try to go the worse it will get.
However the same image printed 2.5”x3.5” will look excellent as there are ample pixels to describe the image if printed that size.

So knowing the size the images are to be printed within the book is as important as knowing the actual pixel size of those images.

[Fixx]

I think Lulu should handle vector content in its printing service just ok. No need to go pixel images.