Scaling a .jpg image using specified number, such as 50%

[Engineering_text]

I'm importing jpg equations and want to downsize the equations in a repeatable manner. In Scribus, I could place the image into a frame, and then use the properties menu (in Scribus) to resize the image. Within the properties I could specify a scale, such as 20%, and the image would be reduced in size and report a higher DPI -implying the same file pixel resolution, just smaller on the Scribus page. This scaling would not affect the frame the image was placed in.

Is there a way to do this in Affinity Publisher? I hoping to not have to edit the equations in a separate graphics program.

1. Resize by entering a number such as percent scale. DPI should change, not number of pixels.

2. Resize independent of the size of the frame I import it into.

thanks

[Engineering_text]

Looked around again and saw where after selecting the object, no need to right click or search through menus. A tool bar near top of the screen displays the pixel size and percent in a cell toward near the left. Clicking the little carrot in that cell, opens a drop down set of options which includes setting the scale. This does exactly what I was requesting. Always obvious, once I know the answer.

Helpful that another user's post shared a screenshot that showed the pixel and scale cell while discussing a different scaling issue.

This option is not displayed until the image has been selected. Logical. The problem was with me. I would right click on the item to get a menu of properties. When I didn't see what I wanted in that menu, I then left clicked elsewhere on the screen to dismiss that menu -which then made the very feature I was looking for disappear. I'll have to get used to looking everywhere on the screen after I click on something. The lack of questions on using this feature indicates I am an outlier, and not in a good way.

I do love the amount of support I get from the kind and patient people here.

 

[John Rostron]

I could tell you how to do this in Photo, but I am not a Publisher expert so I will leave that to those who know.

On 5/4/2022 at 10:06 PM, Engineering_text said:

Resize by entering a number such as percent scale. DPI should change, not number of pixels.

What puzzles me is your requirement here. You should be aiming to have your image dpi the same as the rest of the document, which may involve changing the size in pixels.

John

[thomaso]

1 hour ago, John Rostron said:

You should be aiming to have your image dpi the same as the rest of the document, which may involve changing the size in pixels.

Why that? Such a resizing would be destructive and cause a loss of initially available pixels. What advantage or even need do you see in that modification?

In all Affinity apps you can have layers of the type "(pixel)" or "(image)". The good thing about a downscaled image layer is its possible reserve, while a pixel layer never contains more than is displayed at 100 % zoom level.

[John Rostron]

I was basing my assertion on my experience. When I placed an image into Publsher with unmatched dpi, it has always printed with lower quality than if I match the dpi. I prepare the image in Photo to the required physical dimensions, specifying 300dpi.

I would be happy to be told if I am doing this wrong. As I said earlier, I am not a Publisher expert.

John

[Engineering_text]

John R: I also prefer to create the images to match the final dimensions in the desired dpi. I like a consistent look to line art throughout the chapters: Consistent lines weights, fonts, font sizes, etc. in the illustrations. In this case, I have had bad luck with equations in vector format inserted into desktop publishing software. No problem with line art, but big problems with equations. Not a pro at this, so not going to learn Tex or Latex. Exporting equations as windows metafiles works badly. Exporting as EPS I've had somewhere in the process the thumbnail image (looks like bad 9-pin dot matrix image) get used instead of the postscript info when it prints or the document is converted to pdf.  For equations, I get consistent results by converting to jpg. Nothing misinterprets jpg -so far. Unfortunately, the equation editor (only one I found that exports to jpg) has few options when exporting to jpeg and so only provides a limited number of discrete pixel sizes expressed as "dpi" without also referencing dimension. So it's a little clunky to import the equation and then scale by 89% to get the font back to 10pt size, but at least it has me down to just two programs instead of trying to pull the equations through Corel Draw. As I said, I have no problems with importing vector line art, but all the brackets, and special characters, in equations are fonts and they get horked up. So I go with raster images to avoid misinterpretation. 

[thomaso]

9 hours ago, John Rostron said:

When I placed an image into Publsher with unmatched dpi, it has always printed with lower quality than if I match the dpi. I prepare the image in Photo to the required physical dimensions, specifying 300dpi.

I would be happy to be told if I am doing this wrong.

I assume you mean any output, regardless of print or export? (I am not experienced with printing from Affinity).

If you watch the image unscaled and at 100 % in APhoto and use it scaled in APub then they do and must differ. But the image also differs before / after scaling if you scale the image in APhoto first. It is the scaling which manipulates pixels, not the use in APub in particular.

1 hour ago, Engineering_text said:

Exporting as EPS I've had somewhere in the process the thumbnail image (looks like bad 9-pin dot matrix image) get used instead of the postscript info when it prints or the document is converted to pdf. 

This is a matter of the app you export from, right? – Affinity can handle EPS and PDF vector data without rasterizing them on import or output, means if you place vector data in APub you can export them as vector data without quality loss.

Concerning text, font sizes and stroke / line width: yes, the document resolution matters, a certain size varies with the document resolution. For instance if a text example with 24 pt size has in a 300 dpi document a height of 91.75 px then the same text and fonts size has in a 72 dpi document a height of 22.02 px – which means the latter would need to get upsized if copied / placed into a 300 dpi document. But since Affinity keeps it as vector (if it is placed as vector) the resizing doesn't influence the quality, it is possibly the required calculation for the according scaling factor which may confuse or disturb in this workflow.

In Affinity you can either adjust the size in your unit or as calculation / expression in the Transform panel, or you can adjust the DPI or % scaling factor of the placed resource in the Context Toolbar (as you noted in your 2nd post in this thread).