Resizing a document WITHOUT changing the DPI-value and WITHOUT resampling

[Dreamer]

Hello again,

I hope this doesn't sount like too stupid a , but I would like to resize JPEGs and PNGs without changing the DPI-Value and without Resampling. Is there a way to do that?

Because I know that the picture qualitiy is high enough to zoom in immensely. So I would like to take a few pieces of the picture - say for example 3 inches by 3 inches and I know they will still look good when enlarging them by a factor 5. In other words, that little piece will still look good when printed as 15x15-inches picture with 300 dpi. (the original picture also has a dpi of 300.)

But I cannot simply upload the original 3x3-piece - I get an error message.

So really all I would need is a way to change the metadata of the picture: the values for hight and width. But I haven't found a program yet that will allow me to do this. In Affinity Photo's Macro Lirbrary there is a macro called "Strip Metadata" so I guess I can use the Programm for working with Metadata as well?

 

Thank you very much for your help and kind regards,

Dreamer

[firstdefence]

2 hours ago, Dreamer said:

I hope this doesn't sount like too stupid a , but I would like to resize JPEGs and PNGs without changing the DPI-Value and without Resampling. Is there a way to do that?

1. Select the area you want, copy it ⌘+C
2. Create a New document using File > New From Clipboard

[walt.farrell]

3 hours ago, Dreamer said:

Because I know that the picture qualitiy is high enough to zoom in immensely. So I would like to take a few pieces of the picture - say for example 3 inches by 3 inches and I know they will still look good when enlarging them by a factor 5. In other words, that little piece will still look good when printed as 15x15-inches picture with 300 dpi. (the original picture also has a dpi of 300.)

That doesn't sound possible, to me. Or I don't understand what you're asking for.

First, a picture is just pixels, and doesn't really have a DPI intrinsically. DPI only comes into play when you're printing it, and all the picture really has is a pixel count. That is, if you have a picture that is 600px by 600px then it has 360,000 pixels and  it's just a square, with no intrinsic size.

You can say that you want to print it as a 2" by 2" picture, and at that point you know that when printed it must have 300 DPI, because 600/2 = 300. Only when you specify the output size do you know what the DPI must be.

Or you could say that you want it to be 6" by 6" picture, which would mean that when printed it would have 100 DPI, because 600/6 = 100.

Now, suppose you crop that picture to give you 300px by 300px.

You could print it as 1" by 1" (with 300 DPI), 3" by 3" (with 100 DPI), 6" by 6" (with 50 DPI), etc. You have one set of pixels, and without making more of them (resampling) the print size is determined by the DPI you choose to print at. You cannot take that "chunk" of pixels and print it larger or smaller while keeping the DPI  the same and without resampling. If you don't resample, you either have to change the DPI or you have to keep the size the same.

[toltec]

You are not resizing it, you are just changing the view size, or zooming. That depends on what you are viewing the image in.

When you say "upload, upload to where ?

This may be off track, but one thing about Affinity is the way it places images. The placed images can be at a much higher resolution than the main canvas. If you then export as slices, you can set the slices to use this higher resolution, the main canvas resolution, or both.

However, 5 times is really too much to be practical. Best to save one image as 15" x 15" and output smaller images from that as you need them. Re-sampling as you do.

It just depends on what you are using the images for.

[IanSG]

15 hours ago, Dreamer said:

In Affinity Photo's Macro Lirbrary there is a macro called "Strip Metadata" so I guess I can use the Programm for working with Metadata as well?

Metadata is things like camera details, date, location etc - look for "exif data".  Height and width aren't metadata so that's not going to help you.