Page 1 of 1

Cropping

PostPosted: Thu Jan 20, 2005 8:24 am
by Hlop
Another stupid question ...

How are you cropping your pics if you want to keep proportions without resizing image. For example, when you're using Crop Tool in PS, it allows to set width, height and resolution but with this method you resize pic. Is there any quick way to use marquee tool to keep proportions and resolution but no resize?

PostPosted: Thu Jan 20, 2005 8:49 am
by leigh999
Actually I have wondered that myself...

When I don't want to resize/resample something but still make a crop I go to image/image size and make sure that the resample image box is not checked, and then use the crop tool and set the width and height then the image won't be resized/resampled. The resolution will be changed to acheive the correct print size.

So if you had a 10 x 8 at 250 dpi and then you crop the image but still have the dimensions 10 x 8, then the resolution will be adjusted down to say 200 or 150 dpi to give you the exact print dimensions you want. But you haven't taken away or added any pixels.

I am not sure if that is what you are asking though... Sorry if it is no help!

PostPosted: Thu Jan 20, 2005 9:07 am
by Hlop
leigh999 wrote:So if you had a 10 x 8 at 250 dpi and then you crop the image but still have the dimensions 10 x 8, then the resolution will be adjusted down to say 200 or 150 dpi to give you the exact print dimensions you want. But you haven't taken away or added any pixels.

I am not sure if that is what you are asking though... Sorry if it is no help!


Sorry, I probably incorrectly formed my question ....

If I have an image 3008x2000 and 300dpi, and I want to cut off some unwanted things but keep image in 3x2 proportion (not 2x2, 2x1.5 or anything else), so, how I crop it to keep 300dpi but smaller size after cropping?

In your solution, we're loosing image quality because there are less dots per inch but good point, yes, we're not resampling it.

PostPosted: Thu Jan 20, 2005 10:15 am
by ru32day
Hope I understand the question correctly.

1. Open image in photoshop
2. Select crop tool
3. At top of image, you have the option of entering the size to which you wish to crop - eg 15cm x 10cm at 300dpi.
4. After entering the desired settings, draw with the crop tool on to the image. Your crop will be constrained to the size you entered. You can move the cropped area around the picture to your liking.
5. Double click to accept the crop.

This answers the later question. In answer to the earlier question about doing this without resizing, this technique does not resize the shot, it merely "cuts off" the bits you have cropped off, leaving a smaller number of pixels.

You can resize the entire shot to make it a smaller physical size by increasing the dpi (eg a shot half the size with the same number of pixels would be double the dpi of the original). When you crop the shot you will, however, lose the same proportion of total pixels, no matter what you do. The only way to crop and end up with the same number of pixels as you started, is to crop with a higher dpi than the original, which will involve an interpolation (and thus a probable loss of quality).

PostPosted: Thu Jan 20, 2005 10:33 am
by MHD
I dont use PS... I use a very similar (and infinately cheaper) tool called the GIMP...

in GIMP you can select a region with set aspect ratio... So depending on the output medium I can select the correct ratio (35mm vrs graphic design standards, eg 4:3)

PostPosted: Thu Jan 20, 2005 10:40 am
by Hlop
OK. Let me try to rephrase it again.

I want just draw marque tool (or crop tool) and keep proportion 3x2 while I'm drawing and then cut unwanted bits off.

If you make settings in Crop Tool toolbar empty It does cut the bits without resampling but it doesn't keep proportion. The same about Rectangular Marquee Tool - you draw it freely and just cut unwanted bits off without resampling. But it doesn't keep proportion too

If you change anything in tool's toolbar it affects quality and that is not what I want

PostPosted: Thu Jan 20, 2005 10:42 am
by Hlop
MHD wrote:in GIMP you can select a region with set aspect ratio... So depending on the output medium I can select the correct ratio (35mm vrs graphic design standards, eg 4:3)


Yeah, that's what I want but in PS if possible

PostPosted: Thu Jan 20, 2005 10:44 am
by sirhc55
4:3 is a TV standard not a graphic design standard. In fact in graphic design there is no set standard.

If I am producing a catalogue or brochure I crop, resize and do what is necessary to have the image within the size on the page. The only consideration is that the dpi matches the lpi for printing. That is why 300dpi is so important in design as it matches the 150lpi of printing. Conversely, if I am going to newsprint I could work with a lower dpi as the final is anything between 72lpi and 90lpi. Colour in newspapers is often 100lpi therefore you could get away with 200dpi. Again, there is always leeway and the 240dpi the D70 produces can be used for 150lpi.

If you want to print litho at high lpi such as 175 or 200lpi then your dpi needs to be higher.

Chris

PostPosted: Thu Jan 20, 2005 1:01 pm
by lukeo
When you crop something you are cutting pixels off .. you will always lose quality even if you re sample (resize) the image back to it's original pixel dimensions. It's just like using the dreaded digital zoom on Point and Shoot camera's .... you are sacrificing pixels to get closer to your subject.

I understand you want to keep constant ratios so when you have your digital images printed or do it yourself they dont get cropped even further.

I just use the winblows calculator, if the dimensions of the image can be divided by 4 and 3 respectively give or take 0.25 of a pixel then all is well otherwise some more cropping is needed.

The GIMP is great with its tool and i'm sure there are some perspective cropper plugins avail for PS you'd have to search for them I don't know any specific ones.

PostPosted: Fri Jan 21, 2005 12:57 am
by ru32day
I don't understand what you are saying about settings in the crop tool affecting quality. So long as you crop at the same dpi as the original, you will just be left with a smaller picture at exactly the same quality that smaller part of a bigger picture was when you started. The quality should change only if you crop at a different dpi from the original.

PostPosted: Fri Jan 21, 2005 5:42 am
by atencati
wow, this one took me awhile to figure out, I haven't really used it much. In PS CS, to maintain aspect ratio of an image taken directly from camera (2:3) open the image. Select the crop tool. on the top menu bar, click the explanding menu next to the crop tool. select the crop 4 x 6 inch 300 ppi selection. This will let you maintain an aspect of 2:3 and use the drag and crop. if the image is landscpae format, make sure the top reads width 6in height 4in. If it is Portrait format, click the 2 opposing arrows between the porportions and they will swap. Clear as mud?????

hope that helps.

Andy

PostPosted: Tue Feb 08, 2005 8:41 am
by Hlop
Just FYI - I found an answer

To cut pixels without any processing or interpolation, select "Marquee" tool and in the toolbar change "Style" from "Normal" to "Fixed Aspect Ratio"

Andy,

What you described does image resampling and what I needed is just to cut unwanted parts without affecting image quality

PostPosted: Tue Feb 08, 2005 9:12 am
by Matt. K
Mikhail
Easy peazy. Open your image. Click on crop tool. Click on {front image] on top toolbar and the crop tool is now set to maintain the aspect ratio.

PostPosted: Tue Feb 08, 2005 9:20 am
by Hlop
Matt. K wrote:Mikhail
Easy peazy. Open your image. Click on crop tool. Click on {front image] on top toolbar and the crop tool is now set to maintain the aspect ratio.


Disagree. It will maintain aspect ratio but what it does? It crops the image and then increses it to specified size i.e. resampling it. I don't want resampling, especially in case if I'm cropping to much. I want just cut picture like you're doing it when you're cutting photo from the magazine with scissors :) Left pixels aren't changed. So, that is what marquee tool with fixed aspect ratio does

PostPosted: Tue Feb 08, 2005 9:47 am
by Deano
If I understand your problem correctly, the trick is to specify the height and width in the crop tool as inches rather than pixels.

- If you specify pixels then the resolution remains constant which means resampling.
- Specify in inches and the resolution changes which means no resampling.

Take your pick.

Cheers
Dean

PostPosted: Tue Feb 08, 2005 10:38 am
by Hlop
Deano wrote:If I understand your problem correctly, the trick is to specify the height and width in the crop tool as inches rather than pixels.


Actually problem IS solved :)

I didn't want to specify size in pixels or in mm because I didn't want any resampling. What I wanted to crop without resampling and keep Aspect Ratio. So, as I mentioned, you have to change style of marquee tool to Fixed Aspect Ratio, set it as you need (3:2) and then select and use Image->Crop. It has nothing to do with Crop Tool

PostPosted: Tue Feb 08, 2005 11:06 am
by pippin88
I'm so confused.

I use PS 7.

To crop with the right aspect ratio I'd simply been using the select tool and a fixed size (missed the whole fixed aspect ratio setting - stupid me) and then going image, crop. Are you telling me that this resamples for some reason? Why? What does resampling actually mean and whats it for?

PostPosted: Tue Feb 08, 2005 12:30 pm
by Hlop
pippin88 wrote:I'm so confused.

I use PS 7.

To crop with the right aspect ratio I'd simply been using the select tool and a fixed size (missed the whole fixed aspect ratio setting - stupid me) and then going image, crop. Are you telling me that this resamples for some reason? Why? What does resampling actually mean and whats it for?


No, I'm not telling that :)

There is a crop tool and there is marquee tool. Crop tool is resampling image when you're specifying size and resolution or you have to very precisely calculate your crop. Marquee tool with specified fixed aspect ratio does selection with specified proportion and when you do "Image -> Crop" menu it doesn't resample image it just crops, leaving picture untoched.

Wow. I think it should be clear now :) I hope :)

Marquee tool with fixed size style set doesn't resample image as well - it's just less flexible but it's purpose bit different

PostPosted: Wed Feb 16, 2005 8:20 am
by Matt. K
Mikhail
You started a very interesting thread here and I think everybody learnt something. Great stuff!

PostPosted: Wed Feb 16, 2005 9:01 am
by MattC
Yep, I have been using the crop tool for so long that I had forgotton the marque tool and image>crop. That has sorted a problem that I was having with control over resampling. Thanks Mikhail.

Cheers

Matt