Specify selection size

[HaDAk]

When using the rectangular marquee tool, sometimes I know the exact pixel dimensions that I need to be selecting.  I would like to have the ability to specify a selection box size and/or ratio, rather than simply dragging an area.

[carl123]

Can't you use the Transform Panel (W & H values) to do this?

Or am I misunderstanding what you want?

[HaDAk]

Yep; I think you're misunderstanding.  Let's say I have a photo, and I want to select a 100px x 100px area of that photo.  I have no way to precisely do that.  I would like to be able to specify in the marquee tool that I would like that exact pixel size of a selection.

[MEB]

Hi HaDAk,
Draw the rectangle with the rectangle marquee tool first (size doesn't matter at this point), then go to the Transform panel and set the values you want for the width and height. The marquee selection will be adjusted accordingly. Then position the selection marquee where you want. There's no way to set the values before creating the selection marquee unless you prefer to draw a rectangle shape with the dimensions you want, convert it to curves, switch to the Pen Tool and convert it to a selection by clicking the Selection button in the context toolbar.

[HaDAk]

Ah, ok.  That works.  It's pretty counter-intuitive, but it solves my problem.  I don't suppose it's too much to ask for a way to specify a ratio, rather than a pixel size? Say I want to select a 4x3 box, but I don't know what pixel dimensions?

[lepr]

.

[HaDAk]

And this workflow doesn't seem the least bit insane to you...?

[lepr]

.

[svinto]

Have to agree with HaDAk. This is something I do ALL THE TIME in Photoshop, define a size in pixels and then cut out a recatngle with that size from a bunch of photos. Or sometimes define a ratio (H:W) rather than exact size. My employer have recently forced me to switch to Affinity because of Adobe's prices, but I would very much appreciate to be able to predefine the marquee size as with Adobe programs.

[mac_heibu]

Why on earth should this be „counter intuitive“? Because Photoshop does it in a different way?

If you use a different application, you have to learn/accept different approaches to a subject. The“Transform“ approach is a completely logical way of resizing an element/a selection. You can’t really expect a serious application to copy its competitor.

If it is too heavy to learn/accept different ways to solve a problem, then perhaps Photoshop would be the road to go …

[svinto]

On 10/16/2018 at 12:46 AM, anon2 said:

Well, I didn't use the wording "counter intuitive" and I don't expect that all programs should work the way I'm used to. I'm perfectly happy to learn new ways, but once I have, I should be allowed to comment on how well it suits my work flow. When you do a repetitive task, such as cutting out a rectangle of a certain size from a large number of images, it saves a lot of key strokes and reduces the risk of mistakes if I can first define the cutout size and then just click away, rather than having to redefine the selection size in each case.

I would indeed have preferred to stick to Photoshop & Illustrator, but since this is my work and my employer have decided to switch to Affinity I just have to suck it up. That said, I'm generally happy with the Affinity programs and apart from the occasional missing feature they work fine.

 

[Jeff Laing]

On 10/16/2018 at 2:29 AM, MEB said:

Hi HaDAk,
Draw the rectangle with the rectangle marquee tool first (size doesn't matter at this point), then go to the Transform panel and set the values you want for the width and height. The marquee selection will be adjusted accordingly. Then position the selection marquee where you want. There's no way to set the values before creating the selection marquee unless you prefer to draw a rectangle shape with the dimensions you want, convert it to curves, switch to the Pen Tool and convert it to a selection by clicking the Selection button in the context toolbar.

Late to the party here, but what I've noticed (in the version I'm running) is that I set the transform size explicitly to 1500x2100, copy, new from clipboard and the resulting image is 1501x2102.  That isn't too helpful...

[MEB]

Hi Jeff Laing,
Welcome to Affinity Forums
Can you please check if the layer's X,Y coordinates (from where you are copying the selection) and wdith/height are integer values? Thanks. I'm only able to reproduce it in these circumstances.

[Jeff Laing]

According to the data entry form, I was definitely on integer coordinates. Perhaps the user interface is hiding fractional pixel positions for me.

It was so predictable that I just used 1498 x 2098 as the size and regardless of where I dragged it from, I got 1500x2100.

 

[MEB]

Go to Affinity Preferences, User Interface section and change the Pixels value to 3 or 4 in the Decimal Places for Units Types section to increase the decimal places displayed in the UI.

[Jeff Laing]

Tried it, didn't seem to make a difference.  I tried to upload a sample but it >150MB and it was taking forever.

I suspect that it might be because the document is a 600DPI PNG (that I am copying from) - I can imagine where Copy Merged is perhaps downscaling the pixels for some reason and going fractional, in which case "please don't do that either"

[Jeff Laing]

There ya go.  This time the selection shrinks by 5 pixels when you copy merged/new from

demo.afphoto

[MEB]

The layer from you are copying from has only 150 x 205px. That's what's copied to the clipboard

Checking a few things.

[carl123]

Your document has a transparent background

Your selection is 5px taller (at the top) than any actual pixels on the page, hence you have a 5px strip of transparent nothingness at the top of your selection.

When you do a New From Clipboard it only copies actual pixel data not the 5px strip of nothingness hence the reason the height (appears to) shrink by 5px

If you take your document and do a Document > Clip Canvas you will see that your document is actually only 150 x 205px  whereas your selection is 150 x 210px. (Make the background transparent to see this better)

 

The above explains the discrepancy in the document you uploaded but not the discrepancy in your original post, we would need to see that document to see what is happening there.

[lepr]

5 hours ago, Jeff Laing said:

According to the data entry form, I was definitely on integer coordinates. Perhaps the user interface is hiding fractional pixel positions for me.

It was so predictable that I just used 1498 x 2098 as the size and regardless of where I dragged it from, I got 1500x2100.

 

The oversized result does have an explanation. 

A pixel selection, a pixel mask and a channel of a colour raster image are each equivalent to a greyscale raster image. Resizing any of these raster objects involves resampling of pixels, which results in blurring of previously sharp boundaries, and that's why your resized selection became larger than specified in Transform panel.

To see that in an exaggerated form, zoom in and drag out a 10 x 10 pixels selection with Rectangular Marquee Tool. Now resize the selection while RMT is active by specifying 100 x 100 pixels in Transform panel. Add a pixel mask to the document - the mask will be derived from the selection. View the mask by opt/alt-clicking its thumbnail. You'll see that the mask and, therefore, the resized selection, is an extremely blurred square occupying 110 x 110 pixels despite the marching ants enclosing 100 x 100 pixels.

In case you were unaware, it's important to realise that marching ants enclose regions where the selection intensity is greater than 50%, rather than regions where the selection intensity is simply greater than 0%.

[Jeff Laing]

While I appreciate all the technical detail, that really is just an excuse.  I explicitly entered the size I wanted selected - not a general idea of what I would like it to try for.  Remember that it was Affinity that suggested that this was a method that could be used to get a specifically sized selection back in Oct 2018.

(My example was actually made from a new document which I assumed was filled with white, since I had done nothing to it other than "new document, make a selection, try to copy, damn error, add a layer, try to copy, damn errors, paint tool to slap some colour over the selection but it constrained the painting to the selected area, not to a few fractional pixels outside the area like copy apparently does.  I am mildly annoyed that it thinks I wanted the selection snapped to content, rather than the area I explicitly chose - perhaps I'd like the blank background copied as well - or is that a copy merged vs copy problem?)

In the "expanding" case, I was *NEVER* selecting from an area that had no pixels.  It was always a subset from the middle of the image.  I was probably zoomed out because I needed to see the entire image segment I was copying, and because you can't easily/accurately grow the selection larger than screen size if you are zoomed in.

So, what is the solution if I have a hi-res page of (say) 20 playing cards and I want to accurately select each card using a rectangle (that I need explicitly sized to ensure they are all the same), then drag around?  It sounds like you are saying I can never reliably have both size and position because Affinity will fuzz the selection if I start zoomed out.

[walt.farrell]

16 minutes ago, Jeff Laing said:

My example was actually made from a new document which I assumed was filled with white, since I had done nothing to it other than "new document,

That's an incorrect assumption. A new document (File > New) has nothing in it. That won't be obvious unless you tell Affinity to display it as transparent, but it will be empty nonetheless. 

If you want it to actually be white, you can add a Fill layer.

[lepr]

 

32 minutes ago, Jeff Laing said:

While I appreciate all the technical detail, that really is just an excuse.  I explicitly entered the size I wanted selected - not a general idea of what I would like it to try for.  Remember that it was Affinity that suggested that this was a method that could be used to get a specifically sized selection back in Oct 2018.

(My example was actually made from a new document which I assumed was filled with white, since I had done nothing to it other than "new document, make a selection, try to copy, damn error, add a layer, try to copy, damn errors, paint tool to slap some colour over the selection but it constrained the painting to the selected area, not to a few fractional pixels outside the area like copy apparently does.  I am mildly annoyed that it thinks I wanted the selection snapped to content, rather than the area I explicitly chose - perhaps I'd like the blank background copied as well - or is that a copy merged vs copy problem?)

In the "expanding" case, I was *NEVER* selecting from an area that had no pixels.  It was always a subset from the middle of the image.  I was probably zoomed out because I needed to see the entire image segment I was copying, and because you can't easily/accurately grow the selection larger than screen size if you are zoomed in.

So, what is the solution if I have a hi-res page of (say) 20 playing cards and I want to accurately select each card using a rectangle (that I need explicitly sized to ensure they are all the same), then drag around?  It sounds like you are saying I can never reliably have both size and position because Affinity will fuzz the selection if I start zoomed out.

 

I wasn't making an excuse. I don't work for Serif and I don't try to defend their design decisions for the software. Also, I wasn't finding fault with your workflow. All I was doing was providing an explanation for your result not meeting your expectation. 

Solution:

Draw a vector Rectangle object with the required size then press cmd-enter to convert it to a vector Curve object. Position duplicates of the Curve where required. Select a Curve, activate Pen Tool (P) then click the Selection button in the context toolbar to create a pixel selection from that Curve.

 

 

[walt.farrell]

23 minutes ago, Jeff Laing said:

While I appreciate all the technical detail, that really is just an excuse.  I explicitly entered the size I wanted selected - not a general idea of what I would like it to try for.  Remember that it was Affinity that suggested that this was a method that could be used to get a specifically sized selection back in Oct 2018.

Can you give us a screenshot showing the selection (after using the Transform panel to set the size), and including the Context Toolbar, please?

[Jeff Laing]

Start from this

Copy Merged / New from Clipboard results in this