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Batch Resizing of Images

Guest Bloo Dog

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Guest Bloo Dog

I searched the site for an answer but I can't find it.


Here's the situation: I am a photographer. I have photographed in all media and formats. I have supplied images for print and for websites, but I've never run into this challenge one before, at least not of this magnitude.


I will be photographing about 1,000 images for a website. The designer has laid out a lot of requirements, some of which I've never encountered before. The one that has me stumped is this one: the designer specifies that the image must be photographed at 10-15 megapixels. No problem there. The other specification is that each image must be cropped to a specific dimension. Each file must then be drastically resized to 800pixels x some other figure, then converted from .jpeg to a .tif.


I can do all that no sweat, but one-thousand images? My previous photo gigs have required 12-24 finished images at a time. Publications usually want to do the cropping themselves. My experience has been limited to cleaning up flaws in the objects themselves, or in lightening or removing a drop shadow (minor things).


I use PS6. (Yes, I know that I'm behind the times, but it does everything that I need for it to do). Is there a way of doing this in batches? Resizing the image area as well as reducing the file size and converting each file will take me longer than it will take me to photograph the individual 1000 pieces of jewelry.


I have uploaded photos to websites that have resized the images automatically as long as the file size is within a certain range. Can't the designer use a design program to do this?


In addition, the designer wants the images sent in a .zip file. Since the final image at my end will be pretty small, I expect some loss of quality when the image is compressed then opened.


If this has been asked before, I apologize, but i did a search using different terms but came up empty-handed.



Edited by Bloo Dog
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Seems a bit odd that the photos are being shot at 10-15 megapixels, then resized down to 800x600 at 72dpi -- that'll be a huge loss of quality. You could probably get the same results using 6-8 megapixels... Anyway...


Yes, Photoshop 6 does include batch functionality for exactly this task. You should be able to automate that process -- provide photoshop with the folder of files, and it will automatically crop/resize/change file format.


I'd suggest starting with a search on Google of something like "batch resize photoshop 6". You might also want to look at:


-- http://www.sitepoint.com/forums/showthread.php?t=252128 (covers Photoshop 7, so I'm not completely sure it is applicable)


(again, newer version of PS, but I believe the same basic process should apply)


Unfortunately I only have PS 5 and PS CS4, so I can't really give you exact directions.


In addition, the designer wants the images sent in a .zip file.

There shouldn't be any data loss when compressing the file and reopening it -- using a .zip file shouldn't affect the quality in any way.

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You will need to create a Photoshop action to do this. To create an action, open a file then go to Window - Actions. At the bottom of the Actions panel is a bar like in the Layers Panel. Click on Create New Action - 2nd Icon from the right next to the Trash can.


Name your Action, then click Record. From then on everything you do to the open file will be recorded up until you Save As. When you are finished click the last button on the left (square) to stop recording.


To use this action put all your files into a folder then go to File - Automate - Batch then select the action you have created, fill in the relevant folder information, where to find the files and where to save them to and then click OK. Sit back and let Photoshop do all the work.


If each photo needs specific correcting of some sort or different image sizes this will not work. E.g. Vertical images vs Horizontal images - you would need to create a different action for each batch.


That is it in a nutshell, for more info Google for Photoshop actions, there are lots of free ready made ones but you probably won't need those.

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  • 4 weeks later...

There are a few things to remember when doing a batch image resize operation.

Firstly, the same restrictions apply as when you are doing it manually. If you make an image much bigger than it was originally, you will notice a quality degradation. Generally there's no problem making images smaller, but a loss of quality when blowing up images is unavoidable, since the image does not gain any new data, it just stretches what's there!

Secondly, and especially if you are using the 'Constrain Proportions' option, if you have a mix of portrait and landscape images, be careful! If you specify the width for example, and then set Photoshop resizing, the portrait images will end up larger than the landscape images. It might be an idea to separate out the two types and batch resize them in two separate groups.

Lastly, when you hit that 'Ok' button, be prepared to stop using your computer while Photoshop performs the batch resize. To re-dimension the images Photoshop must open each file, and this can be quite a big operation.

You can do other things while Photoshop performs a batch image resize, but I've found that if there are a lot of images, especially if they are large files, then it can cause Photoshop to freeze or crash, so it's best just to be patient where possible.

Once you have selected a set of images to batch resize using one of the methods above, you need to refer to the third frame in the box, titled 'Image Size' First tick the box that reads 'Resize Images'. This will enable the frame. You now need to tell Photoshop what dimensions and resolution you would like the new images to have.

These options work just like those found in the 'Image Size' dialog box available from the 'Image' menu.

Generally I like to specify the width and height in pixels. If you wish to do the same, make sure "Pixels" is selected in both drop down boxes. Then you can enter your values.

If the 'Constrain Proportions' check box is not ticked, you will have to specify both dimensions. This will resize all images according to those dimensions, even if this distorts the image.

If 'Constrain Proportions' is ticked, then you can only specify one dimension. Using this method, you specify either a width or a height, and each image is scaled so that it matches the dimension you specified, and its other dimension is such that the image is still in proportion.

Finally you need to specify a resolution. This is the only noticeable difference from the 'Image Size' dialog box. Here you can only pick from a number of preset resolution values, instead of being able to specify any resolution you like.

Remember that the resolution is stated in Pixels Per Inch (ppi) not Dots Per Inch (dpi).

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