Is it good practice to set the dimensions of an image (in static content), even if I have cropped the image to the correct size and it's container has fixed dimensions and overflow:hidden ?
<img src="" title ="" alt="" width="100" height="100"/>
Generally you should provide the height and width tags, so that the browser can reserve the needes space for the image. Else, the layout may change during the loading of the page.
As you have a fixed size container and overflow: hidden, it probably won't help much though. But even if it doesn't help, it does no harm either. So you should stick with always adding height and width attributes.
http://www.w3schools.com/tags/att_img_width.asp (See the tips under "Definition and Usage")
I don't have hard data to back it up, but I think I have seen browsers that showed a rectangle in the image's place until the actual image was loaded. To show that rectangular area correctly, browser would need width and height data.
Also, some browsers will show a rectangle instead of the image when images are turned off or can't be loaded. For correct sizing of the rectangle, dimension info is also needed.
I think it won't do any harm to set it.
Related
I'm using HTML5's <picture> tags to create a responsive header that will stretch the entire width of the browser. The header uses an image as the background.
For larger screens I limited the height to a defined value. However, I noticed that a certain breakpoint the image starts to stretch and distort the image.
I'm familiar with using CSS's background-image: url(); to create a mask in order to prevent the distortion, but I don't know what best practices are with <picture>.
My code currently stretches and distorts the image. Is there a way to 'mask' the image?
First thing you should know is that if you will give height to any image then in some screens it will stretch.
So instead of giving the height you should take the image of exact size it will do the thing.
If you can share the code I can fix it and send it to you.
Hope it helps.
User zgood was able to lead me in the right direction. Adding object-fit: cover to the <picture>'s <img> tag got the job done.
I found a similar question here, with the answer: "you should always define the width and height in the image tag." But it is from 2009.
In the meantime, many things has changed on frontend. We are all doing responsive page design now, for many devices and sizes simultaneously (mobile, tablet, desktop...).
So, I wonder is it still necessary to specify the width and height attributes, and for what reason (for responsive, page speed, SEO...)?
An img element has width and height attributes, but they're not required under any DOCTYPE.
Width and height attributes were only 'required' or relevant to reserve the space on the page and prevent the page moving around as it loads - which is important. This can be achieved using CSS instead providing the CSS loads quickly enough - it is likely to load before the images anyway, so all should be good.
It is also possible (and valid) to specify just one attribute, width or height and the browser will calculate the omitted value in order to maintain the correct aspect ratio.
You can specify percent values in the attributes if required. You don't need to use CSS for this, if that is what you are implying.
Also, it is relevant to add - Under HTML5 the width and height can only take a pixel value, in other words a valid non-negative integer.
Whether you use the width and height attributes can depend on your design. If you have lots of differently sized images, do you want to lump all the dimensions in the CSS or include them with the img?
YES, you want to declare the width and the height of an image in 2016.
To make them retina-ready
If you want your image to be retina-ready, you should define a width and an height lower than the actual pixels. If the image is 800x600 specify <img width="400" height="300" />.
To avoid page jump
Without the width and the height the image does not know how large it is, which causes an unwanted jump in the page as it loads (it reflows). Declaring height and width solves this problem.
Note that:
Images with a defined width and height can still be responsive. Simply add max-width and max-height to your CSS. This will cause the image to scale down (not up) when it does not fit the screen (see this sweet retina-ready, responsive kitten). Defining a min-width and min-height will do the opposite.
Adding a huge amount of compression to your JPG (around 50%) to keep the file size low is recommended when you use a single (relative large) image for all screen sizes.
Well, the basic answer to this question (as with most coding issues) is this: it depends on the situation at hand.
I would say that the “best practice” of always specifying the height and width attributes of images making a significant difference to page rendering speeds hark back to the days when designers laid out their websites using tables and spacer GIFs. We have come a long way since then.
An indication for the future is the introduction of the new picture element being drafted into HTML. The picture element is effectively a wrapper for the existing img element, which allows you to specify several images of different sizes via a source element, and the user-agent itself actually determines which version is used.
<picture>
<source media="(min-width: 64em)" src="high-res.jpg">
<source media="(min-width: 37.5em)" src="med-res.jpg">
<source src="low-res.jpg">
<img src="fallback.jpg" alt="This picture loads on non-supporting browsers.">
<p>Accessible text.</p>
</picture>
As you can see from this example code above (taken from the Intel Developer Zone's article on the HTML5 picture element) there are no height or width attributes on the img element itself.
Here are a selection of resources that will help you to decide the most appropriate method of declaring image sizes:
Responsive Images Community Group
W3C Working Group Note: Use Cases and Requirements for Standardizing Responsive Images
WHATWG HTML Living Standard: The picture element
Good standards are always worth a recommendation. With a little extra code it's quite easy to merge static (px) values of the img tag and generic (em, %) values supplied by CSS. And simpler still, get rid of the img tag altogether and set the picture as background of a div with a unique ID. If you have multiple images, use sprites and assign each picture to its corresponding div. Your mark-up sources would then look something like <div id="image_001"></div> - that's all. Scales all by itself; no need for bloatware like JQuery, etc.
If we're talking 'bout responsive, you may use bootstrap (if not, start doing this).
When working with images, you should add the class img-responsive, this will modify the width of the image if necessary and the height will be auto, so if width decreases, height will decrease too.
You will always have an image that keeps the same % of its container and will never loose the aspect ratio.
There's no relation with SEO and image size declarations.
Page speed will be the same always, so if the image is 800 x 600 px, you'll load the full image, even if you declare it as 60 x 40 px.
You must think that, even using img-responsive, the max width and height of this image will be the real size of the image. So if we have a 800 x 600 px image, it will not enlarge it (because it'll become loosing quality).
So in 2016, it's recommendable to NOT declare height and width of an image. Instead use bootstrap's img-responsive class, other responsive framework class that gets the same result, or hand-made the proper jquery and css to reach the same.
Hope it helps!
Yes, It is still relevant to specify width and height attribute on images in HTML.
Images often take longer to load than the HTML code that makes up the rest of the page. It is, therefore, a good idea to specify the size of
the image so that the browser can render the rest of the text on the
page while leaving the right amount of space for the image that is
still loading.
Hence, specifying width and height attribute on image will improve the webpage performance by protecting from delay in loading.
Yes, it is necessary to add height and width attributes to the img tag along with the src and alt attributes to prevent page-jumping. When our page loads, the specified space will be preserved for the image so that the it can occupy that place peacefully.
But, there is another problem that will arise here Responsiveness.
Once we give height and width attribute to img tag, the image will tend to stay in the same height for all screen-sizes which will make the image to shrink.
To avoid this, we need to add height: auto; to the image in the CSS file.
I was checking my website speed at GTMetrix.com. On the Page Speed tab their was a recommendation to specify the image dimensions for images.
I am using a Bootstrap website.
The images on my site currently have the following html
<img class="img-responsive" src="the-path">
Their is a recommendation at GTMetrix that states that these images are missing width and/or height attributes.
I have always assumed that I should not put a specific width and height attribute on my img's when they have the img-responsive class.
Can you advise if width and height dimensions should be included on every img on a Bootstrap website even when the img-responsive class is being used.
The recommendation for setting a height and width exists so that the page does not have to be completely redrawn from scratch with a new layout once the image loads. If you pre-set the image size, then the layout remains the same after it loads, which is more efficient and also prevents somewhat jarring movement for the user as the page still loads.
When it comes to any design, if you expect a dynamic image size and your page can handle that, then there is nothing wrong with leaving the height/width unspecified. It's just an optimization technique. Value a functioning site over optimization.
try to use
http://www.w3schools.com/cssref/pr_dim_height.asp
using properties as: px change to vh(vertical height) or hh(horizontal height)...
example:
height: 80vh;
width: 40hh;
the size of 1 vh or hh depends on screnn size
I'm trying to make a profile picture thumbnail where the image is different for each user. I want to define the dimensions in which the image must conform to. Since the image is going to be different for each user, how would I go about writing the HTML without knowing what the file name of the image is going to be?
Option A: just don't define the size; <img> will be automatically sized and the document reflowed when the image loads. Not pretty, but best you can do if you really have no idea what the sizes will be.
Option B: enter either the height or the width; let the browser scale the other dimension upon load. This is nice if you can fit a fixed height or width in your layout.
Option C: use CSS to specify max width and max height. The image will be scaled to be inside that rectangle. This is nice.
Option D: specify the height and width in CSS. If you have images of different size, they will be stretched, which will look awful.
Option E: same as D, but crop and/or resize the thumbnails so that you know the size in advance. Best option if you can do it.
Use CSS.
Give the image a class and write a CSS declaration like this:
<img class="profilepic" src="path/to/image" />
.profilepic {
width:100px;
height:100px;
}
You can also just put the styles inline if you wish.
<img style="width:100px;height:100px;" src="path/to/image" />
If I know the height and width of an image that I'm going to display with an image tag, should I include the height and width attributes, or just put the information in CSS? Or both?
Ex.
<img src="profilepic.jpg" height="64" width="64" />
or
<img src="profilepic.jpg" height="64" width="64" style="height: 64px; width: 64px;" />
or
<img src="profilepic.jpg" style="height: 64px; width: 64px;" />
According to Google Page Speed, you should always define the width and height in the image tag. But, to validate you can't use the style tag.
Also, you should always specify the same height and width as the actual image so the browser doesn't have to do any modifications to it like resizing.
I'd suggest doing it
<img src="..." height="20" width="50">
Edit: Someone suggested in the comments that it would be faster to just not add any attributes. According to Google (not that they are the end all of browser knowledge):
If no dimensions are specified in the containing document, or if the dimensions specified don't match those of the actual images, the browser will require a reflow and repaint once the images are downloaded. To prevent reflows, specify the width and height of all images, either in the HTML tag, or in CSS. - Read More
Given that, you could do the img dimensions in CSS, but to validate you would have to do it in a CSS file, not inline.
BTW, Google Page Speed is a series of tips focused on rendering the page faster.
You should always specify the height and the width of an image if only to help the browser lay the page out even before the image has been downloaded.
See 13.7 Visual presentation of images, objects, and applets in the HTML 4.01 spec:
The height and width attributes give
user agents an idea of the size of an
image or object so that they may
reserve space for it and continue
rendering the document while waiting
for the image data.
They are recommended and not required but you really, really should specify them ;-)
Also, please make sure the dimensions you specify actually match the dimensions of the image.
There is nothing worse than waiting for a page to download just because those 400x300(!) images are in reality more like 4000x3000 at 95% quality.
Yes you should specify the dimensions, so user agents know beforehand the size before the image fully loads so a layout couldn't potentially look broken if it relies on the loaded image's dimensions. In addition, if you're relying on IE6's filter property to insert png's you will need those dimensions.
This answer is now dated and I wouldn't make the same recommendation as I did back in 2009 with modern browsers.
It doesn't really matter which one you use, but I would recommend using only one.
I would recommend the attribute over the css solution as it is more compatible to older browsers and people with styles disabled.
Actually you don't have to specify them. Accordingly to w3c specification you use them only to override default values that are embedded in the image file and are read by the browser. When used will scale the original image to given sizes so putting them is making an extra calculus for the browser.
The height and width attributes give user agents an idea of the size of an image or object so that they may reserve space for it and continue rendering the document while waiting for the image data.
<img src="profilepic.jpg" alt="image" />