Crop options

[JonE]

Could some of you comment on cropping using the crop tool vs. the rectangular marquee. Of course the crop tool is handier because you can adjust the outline after setting whereas on marquee it's set and either go or cancel and try again. I find using the grid view helps set it right almost every time. The crop tool also lets you use the preset sizes e.g. 4x6, 8x10, or use freeform. I always was using the crop tool until I realized that not only was it using the shape of those pre-sets, it was actually making the photo into that size file. So if I cropped down to a little 2x3 section of the photo, it was making it into a 4x6. Does that mean it's actually enlarging it? Does that matter? Isn't the print size controlled by the print dialogues anyway? And for on-screen viewing like on a web site isn't it the pixel dimensions that count (set by Image>Resize) not whether PSE thinks it is 4x6" during editing. the marquee tool seems to leave the photo the size it is, so is that better (for whatever reason)? Appreciate any help with these questions!

[Wendy]

Hi Jon ...

The crop tool doesn't actually crop to a specific size (as long as the resolution box is left blank) ... it simply crops in that ratio. So the physical size then depends on the resolution ... all you do to sort that out is make sure that your resolution matches the physical size you want when you come to print out. On screen it doesn't matter as it simply shows it as large as it can in the screen space ...

I always use the crop tool ... :)

Wendy

[JonE]

Thanks, but just to check . . . if you start with a roughly 8x10 raw photo, then use the crop tool to crop down to say 1/3 of the size using the crop tool set to 8x10 dimension, it then measures 8x10 on the screen using the rulers along the edges. Are you saying it does not actually make it that size, even though it "measures" that size? I always thought it didn't matter but now seeing this has raised this concern. Thanks again.

[Wendy]

Butch is much better at explaining this than I am ... take a look st this thread ... message No 10 :)

http://www.photoshopelementsuser.com/forum/showthread.php?t=9768

Wendy

[JonE]

Thanks, that's helpful. It's still a difficult area because of the different issues involving original size, physical size and pixel/screen size. Thanks again for the lead.

[Codebreaker]

The main problem with the Crop tool is that you can re-sample the image or change the resolution without realising it, resulting in a loss of quality.

For instance if you specifiy a physical dimension and then crop just a small area the Resolution (PPI) gets adusted accordingly.

If you specify a Physical Dimension and Resolution then the cropped area gets Resampled and this may be by too high a factor.

The use of the Select/Image Crop method gives you more control. In other words neither the resolution changes or the pixels get resampled - its a vanilla crop, just throws away the pixels you don't want.

If you want to work around the problem of not being able to re-size the Marquee try this:-

1. Create a New Layer
2. Fill it with any colour
3. Drop Opacity to 0
4 Transform Selection (Ctrl + T) to suit
5. Throw away New Layer

Colin

[Wendy]

Colin ...

I'm not sure that I follow that ...

I experimented using the same image

1. Used the rectangular marquee and then did Image>Crop

2. Use the Crop tool ... no setting for width/height or resolution (crop area just as I used the rectangular marquee)

3. Use the Crop tool ... setting used for height and width (I simply copied the ratio that 1 & 2 used).

and the resultant images are all identical in both pixels and file size ...

Wendy
PS ... I know that inputting a resolution will change it so obviously I didn't do that.

[Codebreaker]

Wendy.....

For 1&2 the results will be the same. However, if you specify a physical dimension the resolution will change unless you hit exactly the right number of pixels.

For example if crop your image to be 6 x 4 and you enclose only 1200 x 800 pixels the resolution will be 200PPI. (1200/6 x 800/4) If you enclose only 900 x 600 pixels your resolution becomes 150 (900/6 x 600/4) and so on.

If you specify a physical dimension and resolution and don't enclose enough pixels then resampling takes place.

For example you enclose 900 x 600 pixels but want a 6 x 4 at 300PPI then the crop area needs resampling up to 1800 x 1200 ( 6 x 300 by 4 x 300).

Colin

[Wendy]

Hi Colin ...

Even when I set the height and width ratio (but obviously no resolution) as long as I make the crop enclosing the same area as I did in 1 & 2 it still turns out identical to the other two ..

Try it out on an image and you will see what I mean :)

Wendy

[Codebreaker]

Wendy...

I'm not sure what you mean by setting the height/width ratio. Do you mean set a physical size when using the crop?

If you crop by whatever method without any dimensions you are just throwing away pixels and resolution doesn't change but physical size will because they are proportional to each other. This is your 1&2

As soon as you specify a dimension in crop then something has to change unless you hit it just right.

Try the same dimensions in Crop but with two different sizes of crop box on screen. You will see the resolution change. Do the same but specify a resolution as well. You will see the pixel dimensions change.

Colin

[Wendy]

Hi Colin ...

OK let me try and explain again ... I did 1 and 2 then set the height and width to the same size as the image I had produced in 1 and 2. with No resolution set.

When I did the crop the pixel size on each side and the file size are identical ... so if your box is the same size as it is when you use the marque tool then both images are the same ...

Try it out ...

Open up any image, create a new layer above it and draw a box on it. Flatten the image and save it.

Now try and 1, 2 and 3, save the individual ones and see what happens :)

Wendy

[Codebreaker]

Wendy.....

Somehow we're not on the same page :)

Open and image and use the Rectangular Marquee Tool to draw a box of a known pixel dimension e.g. 900 x 600. Goto Image > Crop and the result is an image of 900 x 600 and the same resolution as the original because the Marquee size is exactly what you specified.

Open the same image original image again. With the Crop tool you cannot specify a Crop box that encloses the exact number of Pixels you want. You can specify a number of pixels or inches or cms that you want the Crop to finish up as but you can draw the crop box any size you want (proportionally). So unless you draw the Crop box exactly the same number of pixels you entered. Something will change.

For example, you specify a crop dimension of 900px x 600px in the width/height box but you only draw the Crop box around 300 x 200 pixels. How does it give you a result of 900 x 600 you wanted - it resizes. That's why it looks the same.

Use a physical dimension instead of pixels and the resolution changes.

Draw two different size crop boxes using the same physical size for both - see the resolution change.

Draw two different size crop boxes and specify the resolution the same for both - see the pixel dimensions change.

Colin

[Wendy]

Hi Colin ...

I didn't use pixels ... I used cms which then gives you a ratio not an exact size in centimetres ...

I do understand about resolution which is why I have mentioned several times that I leave it blank :)

OK here is the image ...

1. The original image with the box drawn on it that I will crop
2. The image cropped with the marquee tool
3. The image cropped with the crop tools but no settings
4. The image cropped with the crop tool with a width height ratio set (which is in the ratio of 20.11 cm x 19.87 cm) ...no resolution set.

As you can see all the images are identical pixel size and the resolution is the same on all of them ... well apart from me not being 100% accurate when cropping :)

Just give it a try ...

http://www.pixentral.com/hosted/17DnL7KsU6KgHD6WOo0DYdFZThBMSZ1_thumb.jpg (http://www.pixentral.com/show.php?picture=17DnL7KsU6KgHD6WOo0DYdFZThBMSZ1)

Wendy

[Codebreaker]

This is where we need on-line sharing of desktops. :)

If I've understood what you are doing it seems that you have drawn a box (image top left) and are going to use as the same area for each of your crops (that is, it encloses the same amount of pixels in each method)

So your steps 2 and 3 will produce the same result.

In step 4 you have entered a dimension worked out from the result of cropping in 2&3. (Have I got that right?) You put this number in the width/height fields AND draw the crop box to the same dimensions as in 2&3. In which case everything will be the same.

In step 4 leave the dimensions you enter the same but draw a very much smaller crop box. See what happens now.


Colin

[Wendy]

Colin ...

Yes I know what happen if I draw a smaller or larger box :) ... come to think of it if I used the other methods to do a smaller or larger box then the same thing would apply ...

... but my whole point is that with the same sized box any of the three methods of cropping give the same result ... which is why I have never really bothered using the marquee to crop :)

Wendy

[JonE]

I have to agree with Colin, and thanks for cracking the problem I was concerned with. Here are the tests I ran:

Starting image: 3008 x 2000 pixels, 10.029 x 6.667", 300 pixels per inch (ppi)
Results of each test taken from the Image Resize dialogue box after test.
Image reset to original after each test.

1) Marquee tool crop to 5x5" square portion of image
Image is now 1500x1509 px, 5x5.03", 300 ppi

2) Crop tool free form (no dimension preset), crop to same 5x5" square
portion of image [clarification: no resolution set]
Image is now 1500x1509 px, 5x5.03", 300 ppi [SAME AS #1]

3) Crop tool preset to 5x5", crop to 5x5" square roughly same portion of
image (tool would not go to exactly the same lineup places)
[clarification: no resolution set]
Image is now 1428 x 1428 px, 5x5", 285.6 ppi [NOT SAME BUT CLOSE
SINCE SIMILAR DIMENSIONS USED]

4) Crop tool preset to 5x5", crop to much smaller portion of image
[clarification: no resolution set]
Image is now 502x502 px, 5x5", 100.4 ppi [MUCH LOWER DENSITY]

5) Marquee tool to select a similar very small portion of image; used
Image Resize to change image size to 5x5" with resampling checked
and density set to 300 ppi
Image is now 1556x1500, 5x5", 300 ppi [RESIZED KEEPING SAME
DENSITY]

6) Same as #5 but with resampling not checked (density sets itself based
on dimension entered)
Image is now 747x720 px, 5x4.819", 149.4 ppi [RESIZED LOSING DENSITY]

This confirms what I was concerned about, that when you use the crop tool with a preset size [clarification: with no resolution set], it does not just use that proportion, it actually takes the portion you select and expands it to the size of the preset, causing from a small to a very large loss of image density.

It looks what the crop tool does with the dimensions preset [clarification: with no resolution set] is similar to using the marquee tool to select the area using the right proportion, then using Image Resize to set the new dimension without resampling and with loss of image density. In my tests, the crop tool came out with an even lower image density than Image Resize without resampling, however this difference might be due to testing inaccuracies in not selecting exactly the same area.

[JonE]

Now I'm amending my prior message by noting that in my tests with the Crop tool, I did not have a resolution set in the tool options. [I have added this as a clarification in brackets at each point above - I hope this has not made it too confusing!] If you put 300 in the resolution box in test #4, it will end up at 300 ppi (of course).

However, if you are heavily cropping, that step does a large amount of pixel resampling all in one step. This itself can cause a loss of image quality. Scott Kelby in his Photoshop Elements 3 Book shows a method of increasing the size of an image 10% at a time. Scott indicates you can even take a normal size photo and increase it to poster size without significant loss of quality (to the eye, not micro examined). However this has to be done in multiple steps of 10% increase at a time in order to retain the quality. This is explained on pp. 102-103 of his book (a trick which he credits to another digital photo guru).

The difference between cropping while keeping the density the same vs. letting it fall off can not only drastically affect printing -- it also makes a significant difference for the size of the resulting image for on-screen viewing. In a similar test I ran using the Crop tool with no resolution set, the resulting image was 100 ppi and the pixel dimensions were 500x500, which was 5" x 5" in size but was relatively small on the screen at "actual pixel" size. With 300 ppi resolution set for the same crop using Crop tool, the resulting image was (of course) 300 ppi and therefore 1500x1500 pixels in size, still 5x5", but at "actual pixel" size it was more than full screen.

[Crissyc]

I selected a portion of a photo inversed it and desaturated the background. I made a stroke outline of the selection like a frame and want to add a drop shadow or a bevel to the selection which is in the middle of the photo. how do I do this?

[JonE]

Kindly post that question in another, new thread. That will avoid a lot of confusion. Thank you.

[seebee]

I have to admit that I switched to using the marquee tool with a set size to crop a while ago (on most occasions, at least), for pretty much the same reasons JonE mentions. I didn't realize until I checked earlier today that there even was a box on the crop tool to set pixel resolution. :rolleyes: But, I have the same questions about resampling; it seems very unlikely that if, for instance, you want to cut a 5 x 7" section out of a 8 x 10" picture you are going to click & drag the exact pixels out to make 5 x 7" without some sort of resampling going on, even though your end product will have the 5 x 7" size.

In any event, I find I like being able to see exactly what I'm cropping out without doing any click & dragging. Just set your dimensions, tap the screen, and adjust the box around until the composition is what you want. It's too late; I'm set in my ways now! :D

[Wendy]

Hi Crissyc ...

When you start a new thread on this one could you give a little more information and we will give you a hand with it.

Really need to know how many layers you have to your image and what is on each one ... or have you done it all on one layer ??

Either way we should be able to work something out for you ... :)

Wendy

[JonE]

Seebee - don't worry, I didn't realize it either until working on these tests! :eek: