Expanding a selection one pixel at a time on any side?

Forum|Forum|5 years ago
November 27, 2020
2 replies
1995 views

Hi,

I am using Photoshop 21.2.4 20200922.r.323 (2020/09/22).

I have exported a bitmap from a third party application and opened the bitmap in Photoshop. The portion of this bitmap that I am interested in is bounded by a rectangle. The overall dimensions of the rectangle are about 1280 pixels wide by 480 pixels high, but these dimensions will not always be exactly the same (as I hope to be doing this quite a bit). The border of the rectangle is exactly 1 pixel thick on all four sides. I would like to select the entire rectangle (including the border) and crop the image so that it includes just the rectangular portion I am interested in and nothing else. When I use the Selection Tool, given the large size of the rectangle, I am having a hard time sizing my selection so that it precisely inlcudes the border of the rectangle and everything inside the border, but nothing outside the border. It would be very helpful if I could initially make an approximate selection when I am "Zoomed Out" (so that I can see the entire rectangle on my screen), and then Zoom In to the corners of the rectangle and adjust each edge of my selection precisely as needed. If there is a way I can do this with keyboard shortcuts to expand or contract the selection one pixel at a time on any side, this would be ideal. If anyone can tell me if/how I can do this, or suggest an alternate way I can accomplish what I am trying to do, I would greatly appreciate it.

Thanks in advance,

Paul

How to

This topic has been closed for replies.

Bojan Živković11378569

Community Expert

"It would be very helpful if I could initially make an approximate selection when I am "Zoomed Out"

Can you post screenshot with one image open to understand what is your task exactly. There are tools and commands in Photoshop to create initial selection but everything depends on task which one may work for you.

There are and options when transforming selection to make your life easier. Are you aware of Reference point and Reference point location options? Those options are available from the Options bar.

P

PaulKraemer1Author

Known Participant

Hi Bojan and JJMack,

Thank you for your responses and I apologize for taking so long to follow up. I was pulled away by a competing project that was a bit more time sensitive. Below is a bitmap (.bmp) that I exported from a third party application (AutoCAD). The area bounded by the largest of the red rectangles is exactly what I wanted to select (and then crop). When I initially exported this bitmap, the dimensions of this rectangle turned out to be 1280 x 512 pixels, but I did not know this at the time. In order to create a selection (with the selection tool) that would include the border of this rectangle and all pixels inside the border, but no pixels outside of the border, the way that worked best for me was to set the selection style to "Fixed Size". In doing this, I was able to guess at the selection size that would correspond to my rectangle, give it a try, and then use trial and error by adjusting the selection size until I got it just right. I became reasonably efficient at doing this, but I thought it would be nice if with the selection style set to "Normal", there was a way that I would be able to use keyboard shortcuts to expand or contract the selection size one pixel at a time in any direction. I would like to play around with the "Transform Selection" method that JJ mentioned, but at this time, I have managed to accomplish what I had to accomplish in order to move forward with my project. The next time I have to do this, I will look into the Transform Selection method (or any other) that might allow me to do this more efficiently, but I am ok for now. I really appreciate both of your help.

Best regards,

Paul

Bojan Živković11378569

Community Expert

Transform selection does not have keyboard shortcut by default but you can assign it from Edit > Keybaord Shortcuts (Alt + Shift + Ctrl + K).

Once you are in transform selection mode you can use keyboard to expand/contract selection (arrows -1px and Shift + arrows - 10px) just set reference point properly. Zoom in to see what exactly you are doing. With some training I believe you can make your task much easier.

JJMack

Community Expert

The way I do it is I zoom out make a rough selection. The use menu Select>Transform Selection with the transform box active I use my mouse wheel to zoom way in and the space bar to pan the image so I can perfectly set the four side of the control box for transform selection.

JJMack

Sign up

To post, reply, or follow discussions, please sign in with your Adobe ID.

Sign in to Adobe Community

To post, reply, or follow discussions, please sign in with your Adobe ID.

Scanning file for viruses.

This file cannot be downloaded