Shrinking image size and impact on quality

[Libby5E69]

Hi! I am planning to purchase a pdf file from an Etsy seller of a set of four images. However, the size of the images is not a very conventional poster frame size; the images are 16.68 in Width and 35.31 in Height. Because of this, I was wondering if I shrunk the size of the images to a more conventional size via photoshop if this would affect the quality of the images. Any advice or tips would be greatly appreciated! Thanks!

[TheDigitalDog]

If this is a PDF, you can 'rip*' to any size you desire, and within reason, there will be no quality loss. 

* The PDF is rasterized to pixels to the size you specify when you open it in Photoshop. This isn't the same as taking an existing pixelized image and resizing it. 

[Conrad C]

If you shrink a PDF that large for use in a smaller Photoshop document to be printed, generally that is a good thing, because reducing physical dimensions will increase the pixel density (resolution) of any images in the PDF.

By the way, there are two ways to shrink it. You can open the PDF in Photoshop and specify a resolution at that time; or you can create a new Photoshop document at the physical size and final ppi resolution you want and then use one of the File > Place commands to include the PDF as a Smart Object. I prefer the second way, because a PDF Smart Object layer preserves all of its available resolution no matter how often you adjust its physical dimensions on the Photoshop canvas. (If you use the Open method but change your mind about the size, you have to start over and open it again.)

[Stephen_A_Marsh]

Note: There is an undocumented limitation when rasterizing greater than 32000 pixels wide or high, which will distort the result.

[mglush]

Hi! A couple of things to remember as you rasterize your PDF...make sure that when you import it into photoshop that you check the resolution and the color space (RGB or CMYK--depending on what type of printer you will use). Depending on how you are going to print, anything from 240 (absolute mininum) and 300 will work well. I ususally do everything at 300. When you resize your image using Image Size, uncheck the Resample box and as you shrink your image the resolution per inch will go up. You will not experience any loss of quality when you shrink the image.

Michelle