Question about resizing methods

[JoeB]

When working with layers I often paste an image as a new layer on a larger image and need to resize the new layer to fit a specific area. The easy way is to simply use the pick tool and drag the marquee until I get the right size. But long ago I recall being advised that this method can be more destructive to the image being resized than using the resize dialogue. When using the Resize dialogue I always use the Smart Resize option.

Does anyone know whether or not, when using the pick tool to resize, the same Smart Resize algorithm is used that is used when resizing with the Resize dialogue, and whether or not it really is better to use that dialogue for resizing?

My other thoughts go like this: When using the Pick tool to resize a layer you are often dragging in and out as you visually look for the exact size you want. When you let go of the node the image is then sized to satisfaction. But does the in-out manipulation have any undesired consequences, or does PSP simply recognize the size you chose when you released the node without making any interim changes?

Beyond that, I'm sure people often resize, let go of the node, decide they want to tweak the size again, grab the node and resize again. Doesn't that actually mean two or more resizing processes? In that case it would definitely have a detrimental effect.

My own method has been to create a duplicate of the pasted layer, hide the duplicate, use Pick on the visible layer until I finally get the size I want, determine the pixel size of that resized image, delete it, unhide the unaltered duplicate and use the Resize dialogue to resize to the pixel size I finally determined. A bit more time intensive, but does that actually ensure getting a better result, with less degradation, in the end?

EDIT: If, in fact, it pays in final quality to follow steps similar to what I've been doing when resizing then I'd likely develop a script to automate it and reduce the number of manual steps I have to take. I find this is a process (i.e., resizing layers placed on larger images) that I have to perform quite a bit for projects.

[Joelle]

Good grief... talk about "making a rod for your own back"! (Don't know if that expression is known in Canada..) ☺

If the aspect ratio of the new image/layer is the same as the one you are adding it to, there is another way:

New Layer>Ctrl+A> copy the layer you want to add, then Shift+Ctrl+L to Paste into Selection.

Otherwise just keep pushing and pulling on nodes

Joëlle

[JoeB]

Thanks for replying, Joelle, but I may not have explained properly the issue I'm concerned with.

I start with a large background layer which, for example, has some type of pattern that I want to use as the background for a collage. Then I have several images of people, animals, whatever, which will be the objects for the collage, and they are of varying sizes. I paste all of these as different layers onto the larger background. Then I move them around to make a pleasing arrangement. I don't necessarily want all of these images to be the same size when the collage is complete. For example, one image might be in the center as focal point and larger than the others. Then I have to resize each one of them to make them Some of the others are scattered around, and I don't want even all of them to be the same size as each other. So I use the Pick tool to resize, move around, tweak the resizing of one or more of the images as I change the positions, etc, until I am satisfied with the arrangement and sizes of each of the individual collage layers.

So my question is whether all of this resizing using the Pick tool is causing more degradation to the different images than if I actually knew the exact size in pixels that I wanted in advance and simply used the Resize dialogue once on each image to resize to the desired pixel size.

But you did add another question to my original one. If you take an image that is the same aspect ratio as a selection but larger in pixel size, then paste it into the smaller selection, does it resize smaller with the same quality as it would have if you first knew the pixel size of your selection and used the Resize dialogue (with Smart Resize selected) to do the resize before pasting into the selection?

[Jean-Luc]

It is a good question...

I don't have time actually to test but you could do it yourself :
- resize some picture many times with the pick tool (after done, zoom and make a screen capture)
- undo
- resize the same picture with -> Image/Resize in one operation to get the same size as above and make a screen capture to compare both images. If you observe some degradation, you know what is the best method for resizing...

[brucet]

A quick thought. Open your image. Take note of its size and dimensions. Then open your job. Insert your image as a new layer in your job file. Use the pick tool to resize that layer only. When you have the correct size copy and save just that layer as a new image. Open up both your original file and the new resized layer/image. Zoom in to 100% and compare both side by side to see if any 'real' differences are obvious.

I've had a quick try and maybe missing something. But the resized layer, saved as a new image, has lost a lost of information. Mind you I was zooming into 250-300%. So with my quick test the pick tool resizes by throwing away information and lowering the quality. But as I said. I may have missed something!
If size/quality is critical then I would start by resizing all the images to begin with. Making sure they all have the same ppi. Then applying those images as new layers.

They key will be how close are you going to look?

regards

[JoeB]

It is a good question...

I don't have time actually to test but you could do it yourself :
- resize some picture many times with the pick tool (after done, zoom and make a screen capture)
- undo
- resize the same picture with -> Image/Resize in one operation to get the same size as above and make a screen capture to compare both images. If you observe some degradation, you know what is the best method for resizing...

I have already done some tests, just not the ones you suggested.

I opened a large, 200ppi image to use as my background, and a smaller (640x360px) 200ppi png image.
I copied the png and pasted as new layer on the background image.
I used the Pick tool and in one motion dragged the png image smaller then released the Pick tool.
I dragged that resized image into an empty spot on the workspace so it became a new image in the workspace and noted its pixel size (402x226px)

Then, back on the large image, created a new blank layer and created a selection 402x226px.
I copied the 640px image from the workspace and pasted into selection on the large background.
I dragged that layer also onto an empty spot in the workspace to it also became a new image.

Finally, I made one more copy of the png and pasted as new image in the workspace.
I used the Image>Resize dialogue with Smart Size used as the resample method, resizing it also to 402x226px.

Now I had 3 images resized to 402x226 by 3 methods: Pick tool resize, paste into selection resize, and Resize dialogue resize.

Then I save each image in 2 different formats - Jpg and PSPimage using the Save As file option in X7 without changing any of my existing settings. Under JPG dialogue options I have compression set at 1 (highest quality), Standard Encoding, and Chroma Subsampling None. The PSPimage dialogue is set for Uncompressed, compatible with X4 - X7.

I then checked the file size for each from the image information in the Manage mode workspace. The interesting thing is that while there are some differences in the resultant file size for the saved JPGs they aren't that different. HOWEVER, there is a massive difference in the PSPimage file size when comparing the file size of the images resized using the Resize dialogue and those resized using the Pick tool or by pasting into the 402x226 selection. I ran all of these tests twice and the results were identical to the decimal each time. Here are the results:

Pick Tool Resize - Saved as JPG - 102.88kb; Saved as PSPimage - 653.06kb
Into Selection Resize - Saved as JPG - 96.4kb; Saved as PSPimage - 650.97kb
Image>Resize Dialogue - Saved as JPG - 94.58kb; Saved as PSPimage - 291.72kb

The question is: What has this told me so far? I'm not sure, but I have a thought.

PSPimage, uncompressed, should save losslessly. If that is the case, then why is there more than twice the file size for those images resized with the Pick tool or by pasting into selection than the image resized using the resize dialogue?

The intuitive answer would be that there is more image information in the two larger saved results than the smaller one. But while that is likely the case, the question becomes whether or not that is GOOD image information. In other words, noise and artifacts are part of image information and affect file size.

So my thought is that it could be that the extra file size is the result of those two resize methods introducing artifacts (for example, sharpness or other artifacts that are otherwise compensated for by the benefits of the Smart Size/Weighted Average algorithm which is used when using the Resize dialogue to resize.

But that's just my intuitive thought. I hope others will chime in with their ideas!

The bottom line is this: There are various algorithms available for resizing images by resampling. It follows that some are better than others for various images or whether upsizing or downsizing. However, are any of them used when the resize is done with the Pick tool or pasting into selection? If so, which one(s)? Or do you get the best result by actually selecting the algorithm you wish to use (or use Smart Size) in the Resize dialogue?

I know it sounds complicated trying to set this question out in words to try to be specific, but really, it seems to me that the question itself is a relatively simple one. That is, is there any quality advantage to using the Resize dialogue over the Pick tool or paste into selection when resizing an image? And if so, why? And if not, why not?

[MarkZ]

Wouldn't it be nice if a techie from the Corel development team would visit the forum once or twice a week and provide some expert input for questions like this?

[benoitvm]

Jumping in...

Yes I observed that scaling with the pick tool uses a far lesser algorithm than the image resize tool (which has options):
When pasting a 4k image in a 2k canvas image as new layer, then scaling it to the desired size (in this case, somewhat less than thhe target 2k canvas) gives a much softer result than if I first resize the 4k image, then copy and paste it as new layer into the 2k target image.

So I share both your frustration (trade-off between ease of use of the interactive scaling of the pick tool, and quality of the resize tool which requires a much longer workflow for 'interactive' rescaling of an object: resizing the original image to be copied, then copy & paste into the target canvas, then back-and-forth and undo/redo until the desired result is found) and the underlying question:

Is there a way to change the (weak) scaling algorithm used by the pick tool ? A registry hack maybe ?

[JoeB]

It is interesting that you came across this old topic, and glad to see you revived it because it would be nice if a Corel person saw it and answered the question. This topic has had over 1200 views, very few replies, and this is the first that seems to have shown, given your effort, that the Pick tool algorithm seems a simpler one, because that would tend to reinforce my opinion that using the Resize dialogue is always the best resize option. So basically my workflow, while taking longer, is likely the one that produces the best quality image in the end. That consists of:

1) Resize the various image layers on the collage with the Pick tool until they fit to satisfaction;
2) Determine the pixel size of these resized images;
3) Use the Resize dialogue on the original of each of the collage images to achieve that determined pixel size;
4) Use that image in place of the image previously resized by the Pick tool.

Thanks for your feedback!

[Jean-Luc]

3) Use the Resize dialogue on the original of each of the collage images to achieve that determined pixel size;

I'm using the zoom in and out tool on the original image until it matches the size of the copy in the collage (collage must be at 100%).
It gives me a zoom percentage and I apply this percentage.

[JoeB]

3) Use the Resize dialogue on the original of each of the collage images to achieve that determined pixel size;

I'm using the zoom in and out tool on the original image until it matches the size of the copy in the collage (collage must be at 100%).
It gives me a zoom percentage and I apply this percentage.

That will work if you can zoom by very small increments. I haven't tried that so if it does then I'll have to give it a try.

[benoitvm]

Thanks for the workflow tip....until we get a better pick tool resize method or the hidden registry setting to unlock that

[Jean-Luc]

That will work if you can zoom by very small increments.

It doesn't. The smallest step value is 1%. Not possible to put .5 steps... :>(

[JoeB]

That will work if you can zoom by very small increments.

It doesn't. The smallest step value is 1%. Not possible to put .5 steps... :>(

That's too bad. For some of my stuff I need to get sizes within a few pixels. Guess I'll continue with the present process I use.