: Resizing image to real world dimensions this may sound like a really amateur question but I'm trying to resize some images to dimensions in centimetres (10cm height x 15cm width to give you

@Nimeshi706

First understand that resolution + width + height = Print size.

You can't change the left side of the equation and expect the right side to stay the same. From the sound of things you are trying to alter the width, height, and resolution but retain the print size. That's why you are struggling.

If you are not printing these images, the resolution field means nothing. See Here

If you are intending to print these images, then you want a minimum of 240PPI in the resolution field and you do not want to Resample when changing the width and height. This often means you get a width and height (print size) which is different than you anticipate.

When you uncheck the Resample option and subsequently alter the Resolution of an image, Photoshop does not generate new pixels (interpolation). It merely changes the density of the existing pixels in the image. This is done to keep the image quality the same. However, in order to do this the width and height must change to match the new pixel density of the image.

You can do what you are trying to do. However, it is not recommended for print-destined images, and you have to do it in 2 stages....



WARNING: This often results in low quality images.


Image > Image Size check Resample and set the Resolution to 240PPI. Then click OK.
Image > Image Size uncheck Resample and input the width and height you want. Then click OK.


This will get you images at the dimensions you want and the resolution you want. However, chances are very high that the images will not look as good as you think they will. Doing this often results in degradation of the image overall.

WARNING: This often results in low quality images.



While I point out the steps above, you should reexamine the images afterward to ensure they still appear suitable for reproduction. These steps are inherently bad to perform on most print-destined images.

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@Alves566

Simple ratio: PPI = Pixels per inch

Same centimeters with different number of pixels mean different densities of said pixels. The denser the pixels, the highest the quality (resolution). So one of your images might be 72ppi while the other might be 300ppi.

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