Photoshop cropping a specific area from an image without resample?

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richms

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#90077 14-Sep-2011 11:42

I have many images with about 20 products per page that I need to crop into single images.

They are the same item but different sizes, so I need the images to have exactly the same relative size to each other. If I use the crop tool in photoshop it just limits the aspect of the select box to the aspect entered, even when they are pixels, so if I put in 300px and 300px and drag a box, and then drag another box around another it will just resize the box to be 300px.

Is there a tool that will give me a fixed size crop frame, basically when the images are displayed beside eachother the relative size of the products in shot needs to be preserved, which isnt something I can do by eye and I would rather avoid resampling if possible since the images from the supplier are already barely at screen resolution.

Richard rich.ms

timmmay

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#520884 14-Sep-2011 11:45

I'm pretty good with photoshop, but it's a huge app. AFAIK there's no easy way to do that.

I would crop to a fixed ratio, then resize to the size you require.

stevenz

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#521002 14-Sep-2011 15:24

You could script it using the ImageMagick tools but it would still be fairly non-trivial.

@KnightNZ

kautious

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#521010 14-Sep-2011 15:46

1. I would recommend , getting the average size of the images & then in Photoshop create a new template say 100px * 100px @ 72dpi

2. Open the montage of images and using the [square] marque tool select a section (product) on the image containing all products Ctrl+C (Copy) & Ctrl+V (Paste) into the template created.

3. Resizing using Ctrl+T and holding Shift whilst extending the corners of the image (pasted) into the template.
*holding shift maintains the aspect ratio of the image being transformed (Ctrl+T=Transform)

Then repeat steps 2 & 3 until all images have been transferred over.

each time you paste the new image into the template you will notice in the layer palette - that they will be put onto a new layer. after doing this for like 20 images you should have 21 layers (including the background layer)

if you want to spend a bit more time and effort on these you can hide each layer 'by clicking the [eye] (view layer)' on each layer after you paste.

*Also hide the BG layer and you should have a transparent Background.

Next thing to do , well what I do is go through all the images and using the magic wand tool (Select) I try to select the Backgrounds with 1.0px feather (fiddly) but once you get into a roll then all you have to do is [delete] the Bg and the images should be on a transparent background.

4 & 3/4's
if proceeding like this you need to disable the [eye] on all layers and only have it visible on the layer that you are working on.

after this has been done , in CS3 Alt+F+D or CS2 Alt+F+W will bring up a 'save for web' window.
- File > "Save for Web" or "Device"

Select .png (8 or 24) and check file-size bottom right of window.
*if selecting 8bit .png , be sure to set the mat colour to your website's bg colour or it may look fugly.
- alternatively use .png 24bit.

if it is around 10-30kb (maybe a bit biggish) then click save.

hide that layer and un-hide the next one down the list and repeat from step 4 & 3/4's

import into your website and check how she looks :)

if you want to get adventurous then right click on one of the visible layers after cutting out the BG and select 'Blending Options' > there are a few cool features in there to make your mouth water as well.

Chainsaw

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#521076 14-Sep-2011 17:17

rectangular marquee tool? Not sure, try it. In the dimensions box stick the actual picture dimensions in that you want, say 200px by 300px. Be sure to put the "px" in there. Then just one click, not a click and drag.

Then in the menu: Image>crop.

kautious

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#521305 15-Sep-2011 09:16

Chainsaw: rectangular marquee tool?.

Correct.

Chainsaw

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#521388 15-Sep-2011 11:31

Yeah, correct, except in the "Style" drop down, select "Fixed size".

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kautious

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#521588 15-Sep-2011 17:17

have compiled a better tutorial for you to download here;

CS3-Cutout-Tutorial-bob.rar - 4.3 MB

kautious

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#521639 15-Sep-2011 19:18

Please excuse my "Spelliing & Gra'ma" as it was a rush jobby;

and my first attempt at using the Wink screen recorder

richms

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#523382 20-Sep-2011 08:52

Got this sorted. I ended up just using the marquee tool on fixed size (which I had no idea was there) and then doing new layer by copy on each item, then using the absurdly slow script to save layers as files, save them all as PNG's and then open them all up and remove the edges of other products and fix the levels since the ones at the lower corner had a lower lighting than the top corner, then crop the height (since I found the site only resizes based on the width) and it was good enough.

All worked out ok and the friend I am doing it for is happy as.

Richard rich.ms