Screen Capture Image Types

Sorry if this has been asked before but I did a quick search and couldn’t find the answer.

Is there a way to select a different file format for screen captures rather than png?

The reason is many sites and forums prefer to use jpg as the standard and being able to define a different file format within Vassal would save the additional conversion step.

Thus spake “Yojimbo252”:


JPG is a poor file format for screenshots because it’s lossy. A better
solution would be to encourage sites whcih don’t permit PNGs to do so.


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Thanks for the quick response.

Regarding your second point what you suggest may be better from where we sit but I think convincing all the applicable websites and forums to switch to png is a far greater undertaking than Vassal giving the option of which file format the user wishes to use. There’s always going to be a trade off between file size and image quality.

In any case whether png is better than jpg doesn’t really matter from a functionality perspective. Surely giving the user the choice is the best way to handle the situation.

I mean is there any technical reason why Vassal is limited to just 1?

Thus spake “Yojimbo252”:

A modern site should support PNGs. I’m not asking you to convince every
site admin on the internet to change, but you could try working on the
ones where you post.

Providing JPG as an option encourages people to save their screenshots in a
format which is less suitable for screenshots. People who know they want a
JPG will know how to convert the image they’ve saved.

Someone has to write the code to do it. There are many freature requests
outstanding which don’t duplicate functionality easily available in other
common software. As a result, it’s unlikely that any of the regular
developers will get to this soon.

Additionally, as you can see from above, I’m not convinced that it’s
something we should implement at all, but feel free to try to change
my mind.


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All fair points.

I certainly don’t disagree that there are higher priority tasks that will offer greater value to the application at this point in time so I’m not going to try and convince you that this deserves greater attention in the short term.

Regarding your intention to convert others to png, it’s admirable.

However, I’m not sure whether using applications such as Vassal through restricting its functionality is the right way to go about it. I’m a strong believer that demand drives behaviour which is the best way to bring about change, it should never be enforced by restriction.

In any case I’m not here to argue the ethical or moral virtues of either approach and I’m sure you aren’t either.

Thanks for taking the time to respond.

On Apr 16, 2010, at 3:39 AM, Yojimbo252 wrote:

Of course, one could argue that making the screenshots available in PNG is driving demand for the upload sites to support it. If one conforms to their restrictions, how does the demand for supporting a better format ever get off the ground?

That said, one could perhaps have more success arguing for a format that still preserves the most important feature of PNG for our purposes – namely lossless compression. So alternative formats would include GIF or (less appealing) BMP format. These are all bitmap formats that don’t distort the images. In particular for screen shots with line art and text (like just about every game counter and most maps), JPEG is truly horrible.

So I can see a good marketing argument for Vassal not to support JPEG shots, because they will make the resulting screen shots look bad. And it doesn’t do the software any good to have people’s first impression of Vassal be “Interesting, but the graphics are really bad.”

Although perhaps there are sites that don’t support PNG format (particularly if they mainly cater to photographs), I would think that they would at least support GIF (unless they really are photo-only sites). Are there really a lot of sites that allow only JPEG images and no other formats?

[Technical background: JPEG was developed expressly to provide a compression algorithm based on perceptual physiology and psychology that provides pleasing rendition of CONTINUOUS TONE images. This was done by throwing away information that isn’t as important when viewing continuous tone, i.e. photo realistic images. In particular, it does terribly with text and any place where you have sharp transitions and high contrast. But those are precisely the types of images that Vassal deals with. So you really couldn’t choose a worse image format for Vassal screen shots.]

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That’s not driving demand that’s narrowing choice. Driving demand is all about offering something that a user/consumer values higher than it’s alternatives and they choose to take that option.

If a person or site prefers to use jpg rather than png there’s obviously a reason for it. Quality vs filesize is always going to be a trade off and some may choose one way and some may choose another.

Constraining Vassal to png is not going to change their opinion because the site will simply force the user to employ a conversion tool so they must convert the png image to jpg before uploading. All you are doing is punishing the Vassal user by forcing them to have to take that extra step everytime they want to upload a screenshot. So whilst you may think this will change opinions, it won’t. Only the benefits of using png will do that.

Forcing people to change by restriction isn’t the way to go about. They must be allowed to weight up the benefits themselves and then choose which they prefer.

Take a look at the big software developers. They design their products to support a multitude of recognised file formats (including jpg) because they feel narrowing choice is more damaging to the desirability of their products than including some that are less efficient than others.

The point is some sites will choose a preferred format. If png isn’t one of them then Vassal users lose out. I’m not suggesting you have to promote jpg, you can still keep png as the default, but if you allow users to select another format if they wish then you’re broadening the functionality of Vassal which makes it more desirable.

I’m not arguing the pros and cons of various formats. I’m sure what you say is true but it’s beside the point. Let people choose which format they prefer. If png is the better format for whatever reasons then it’s popularity will grow and sites will change the way they view it. If they don’t then that’s up to them but a single application like Vassal isn’t going to change the world through denying choice.

Like I said before let demand drive behaviour rather than trying to force it upon people.

And can I just say I don’t want to come across as unappreciative or anything like that. I think Vassal is a fantastic application and I applaud all those involved in its development.

I can fully understand your intention here in wanting to promote png, I simply feel that this isn’t the way to go about it.

Thus spake “Yojimbo252”:

The reason might be as simple as the admin neglecting to enable PNG
uploads. I wouldn’t attribute the lack of PNG support to an intentional
choice by the site admin unless I knew that to be the case.

Show me some such sites.


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Thus spake “Yojimbo252”:

I’d never tried uploading any images there before. What this would cause me
to do is submit JPEGs at 100% quality (i.e., lossless, uncompressed) in
order to get around that, if I had images which weren’t photos.

I still think you should complain to the site admins, despite that I doubt
it will have much impact. If someone contributes the code for handling
saving to JPEG, I’ll consider adding it, but don’t expect me to get to it
myself any time soon.


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I’m afraid that someone is unlikely to be me as coding is well outside my area of expertise but I do appreciate the fact that you’re prepared to keep an open mind on the subject.

Many thanks.