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Resize an entry - Photoshop
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      Panachallenge Forum -> PanaChallenge -> Tips
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431 posts
  [1 of 4]  Posted: Wed Mar 11, 2009, 18:52 (4336 days ago)
Modified: Mon Jun 22, 2009, 18:02 (4233 days ago)

(admin: this guide was written by rafinmelb -- thanks!)

The Panachallenge rules have two size requirements, a resolution requirement and a file size requirement. The combination of factors sometimes gets new users a little confused and they end up with an image with correct file size but so small on the screen that it cannot be fairly judged or alternately with an image the correct size on the screen but that is over the size limit.

There are a number of tools that allow you to resize images. Below is an example for Adobe Photoshop

The screenshots here are from Adobe Photoshop CS3. Most versions will have the same or very similar screens/facilities.

The first things to note about the Photoshop resize process is that it deals with the two rules above though separate stages. The File/Save for Web or Devices can actually do the whole job in one dialogue; unfortunately it strips out the EXIF information which is a required part of the image files for the Panachallenge.

Before starting I would generally save a copy of my edited file at full size to ensure I can get back to it.

The first stage is to get the pixel size/resolution right. To do this you go to the Image/Image Size menu. You will be presented with a screen something like the one below. What you need to do is change the pixel dimensions of the image; the document size is not relevant for this exercise as it relates more to printing.


Generally a size of 800x600 is fairly good for the standard 4x3 images produced by Panasonic cameras. Of course in portrait it will be 600x800. By keeping the ratio lock (the chain icon to the right of the sizes) switched on, when you change one size it will change the other automatically. I normally recommend that you select the longest size:
* 800 for a 4x3 ratio (it will give a width of 600)
* 900 for a 3x2 ratio (it will give a width of 600)
* 1024 for a 16:9 ratio (it will give a width of 512)
Of course you can choose other sizes but make sure that the sum of the two pixel values is not more than 1600.

It is important that the Resample Image check box is ticked. This then gives a number of possible options. I generally use one of the Bicubic options and generally the sharper images one. The differences between options are fairly subtle.

In the dialogue box above you will notice that there is a size next to the Pixel Dimensions heading. It indicates that this will produce a file size of 1.54M. Ignore this, I have never found it to be accurate.

We have now resized the image in pixels but we also want the right file size. To manage this we go to the File/Save As menu. Generally I give my panachallenge entries a different name by adding a suffix “_pana” to the file name. Once you have done this a dialogue box will appear that looks something like the one below.


Notice the slider under the quality options. You slide that left for smaller files (lower quality) and right for larger files and higher quality. There is no single setting that will be right for all situations, it depends on the details of the image.

I have included a second screenshot to show what happens when I move the slider down. You will notice the the screen shot above indicates an image 211.6k and the one below of 170.1k. Again these are estimates and are not accurate. I always try the one a little above and hope the compression works in my favour. In this actual example when I clicked OK and checked the actual file it told me it was 197k. So I actually got away with the higher value


I might need to go through a couple of cycles of this, resaving the file and adjusting the quality level till I get a file the fits into the overall 250K limit.

Once I have done this I review the resultant file. I might decide that the compression level has sacrificed too much quality. I might then decide to choose a smaller pixel size and would therefore go back to the Image/Image Size menu again. Of course I would revert to my unresized original before a second resize cycle.

Generally the more fine detail in an image the larger it ends up being and therefore the more we have to compromise quality to fit the size criteria. Alternately you can increase quality but decrease size.

A link to some adobe self help references:



1794 posts
  [2 of 4]  Posted: Fri Sep 11, 2009, 13:36 (4152 days ago)


When I put in an entry I try to size it (in inches) so that the whole photo can be seen on the screen. However when the entries are displayed, I find that my 7" wide photo is displayed as 9" wide (for example) so that one has to scroll vertically to see the whole shot.

How do I size the photo so that it will fit on the screen?


362 posts
  [3 of 4]  Posted: Sun Sep 13, 2009, 19:16 (4150 days ago)

 Mepo wrote:

When I put in an entry I try to size it (in inches) so that the whole photo can be seen on the screen. However when the entries are displayed, I find that my 7" wide photo is displayed as 9" wide (for example) so that one has to scroll vertically to see the whole shot.

How do I size the photo so that it will fit on the screen?

Size in pixels, is always my answer. Whilst the image has a physical size the actual size is determined by
1. the actual size in pixels of the image;
2. the resolution (in pixels) of the screen setting

So knowing this you can size a photo so it will fit on YOUR screen. No guarantees that it will fit on other's screens though.

Photos will always look different for people who have different resolutions set. Someone with a screen resolution of 800x 600 will see huge images that they have to scroll around to see. If you have your screen set to 1280 x 1024 you will not have to scroll but some images will be small. I have my screen set to 1152x864 and this works well with the typical sizes of the images on panachallenge.


1794 posts
  [4 of 4]  Posted: Sun Sep 13, 2009, 21:42 (4150 days ago)

Hi rafinmelb:

Thank you for your answer. I should have figured that out! It is a hand on the forehead "Duh" moment :-) My old eyes prefer bigger fonts etc so I don't use the high resolution you do. Maybe I will switch it just for the challenges.

Meanwhile my son's biggest complaint with the new windows 7 is that you are stuck with, what he calls, mammoth icons on your desktop.

I guess I've been spoiled by Xnview. I don't know if you use it but it has to be the best image viewing/management program ever & free too.

Thanks again, Mepo

p.s. I was discussing downsizing of images as per your very helpful guide with my older son. He told me that it is best to reduce your pixels by a multiple of 2 and to only downsize one time. He also said that if you have an odd number of pixels to start then you should delete one line of them first so as to arrive at an even number. He did explain the reasons but I lost that bit. I did try it and it seemed to make a difference for me. You are probably already aware of this but I thought I would mention it. Cheers,

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