image resize

[*mark]

Hi People - I'm trying to resize an image again in AP.. the last time I was advised to uncheck the 'resample' box to avoid pixellation. 

But when I do this, ( and I've tried several times) AP automatically alters the image dpi from 180 to 1316, so I end up with a smaller image but a file size 10 times bigger than I started with, which sort of defeats the object of resizing it.

Then if I bring the image size back down, I get poor image quality I set out to avoid...

What is it I'm doing wrong? Thanks

[walt.farrell]

When you say resize do you mean:

1. Change the image print size, but keep the number of pixels the same?
   or
2. Keep the image print size the same, but change the number of pixels (DPI)?
   or
3. Change the image print size and change the number of pixels?

What is the image's current DPI, pixel dimensions, document units (px, mm, inches) and print size, and what do you want to end up with?

[Oufti]

Hello @*mark,

Please, first answer @walt.farrell but, in case it helps to clarify things, I will just recall something very basic, if I dare…

1) Pixels (which are for "picture elements") are abstract per nature they don't have any dimension.

One could imagine that a picture made of pixels is like a sentence made of letters.

• The same sentence — let's say "The dog of the old gumby widow living next door bit me this afternoon while I was riding bicycle on the street." — can be three feet large on a poster, as well as microscopic in a pharmaceutical notice.
  It is like resizing without resampling : it won't change the number of letters nor the number of pixels, whatever the size it is printed. But per inch, you'll have more or less letters/pixels.
   
• Downsampling would be like "The dog of the widow bit me." You lose details but you need less letters. .
• For upsampling, I let you imagine… But it could also be like "TthHeE  dDoOgG   oOfF (…)"

2) So, resampling can work in two directions: upsampling and downsampling 

• In the first case, it is generally advised not to resample, as it would result in the software having to "create" pixels. 
• In the latter (when downsizing the image, making it smaller in inches), it is not necessary to keep so many pixels. Then it's OK to downsample – not too much.