Image size

What is an image file size?

Images are composed by several dots called pixels, and each of them has a color, represented as a combination of three basic colors (red, green and blue). To store each of these pixels, 3 bytes (24 ones or zeros) are generally used. When an image is large, it may have millions of pixels, and that means storing all information for an image like that in a computer or any device will take millions of bytes.

When a camera or cellphone says it takes 10 megapixels photos, it means that each photo has 10 million pixels (mega = million). And having 10 million pixels means it takes 30 million bytes (or 30 megabytes) to store that photo (which is a lot of space!). If you want to send this photo (or many photos) to a friend by e-mail, it will have to transfer 30 megabytes of data and it will take a while to upload it and a lot for the recipient to download it later.

How can I reduce image file size?

Is there any solution? Yes, there are two main solutions. One of them is compressing the image: compression reduces file size without having to resize the image, but image quality will suffer as you increase compression and start losing more image data.

The other solution is to resize your photo, decreasing the number of pixels it takes to store the image, which reduces it’s file size proportionally. Reducing image size doesn’t reduce image quality, although it may lose some very small details if they become too small.

Photos taken using modern cellphones and cameras usually have over 6 million pixels, while most cellphones, tablets, notebook or TV screens have only about 1.5 million pixels, which means you end up seeing a resized version of the image (you only use the full image if you print it). So if you resize your image, decreasing its width and height to a half, your image would have about the same number of pixels than the screens that will display it, so you wouldn’t be losing any quality or detail at all, even looking at your image in full screen mode.

So remember, if you have a huge photo, you can reduce its file size by resizing it until it’s about 1900 by 1100 pixels, and getting a JPG image with just a little compression (about 95% quality). Doing so, you will get a versatile image with great quality, that you can send to anyone without taking too much time, or spending too much bandwidth on your mobile data plan.

Reduce images is an online tool that allows you to apply both compression and size reduction online to any image, and save the resulting images in different image formats like JPG, PNG, GIF or BMP.

www.reduceimages.com

Комментарии (3)

1. Olga Апрель 21st, 2010 в 22:38

   Я в цифровой живописи новичок. И столкнулась вот с какой проблемой. Рисую в основном в Corel Painter X, размер холста ставлю 4500х3700 pixel и разрешение 300. В процессе работы сохраняю в родном формате rif, а конечный результат сохраняю в tif. Затем в Photoshop делаю предпечатную подготовку, т.е. размещаю на печатном листе А4 (3508х2480pixel 300 dpi), добавляю рамку и сохраняю в tif. Распечатку делаю в дизайн студии. Работы при печати получаются смазанными, текстуры кистей не видно, сплошной блюр. Что с этим делать? Подскажите, пожалуйста, как сделать работы четкими при печати.

2. .moroz) Апрель 21st, 2010 в 23:56

   
   

   К сожалению я мало занимался распечаткой работ на фото. Было дело сделал одну картинку. Да, на руках картина выглядит намного более скудно. Я думаю дело в контрасте исходного изображения.

   Создавая на компьютере, пытаешься довести картинку до максимальной степени насыщенности цветом, а вот на печати это может вылиться как отрицательный эффект.

   Пока у меня только такая идея: Специально занижать уровень насыщенность цвета и не перебарщивать с контрастом.

   ПС.. Про блюр: Именно детализация была ещё терпима при моей печати, размытости я не заметил. Может стоит сменить место печати… Либо маленькое разрешение, но у Вас с этим всё в порядке вроде. 4000 x 3000 это весьма увесисто.. Хотя я сужу по примеру 21 см на 15… а A4 будет побольше. Может в этом проблема?

   Были случаи когда печатал с маленьким разрешением… Вот тогда и было очень размыто +)

3. Olga Апрель 22nd, 2010 в 11:59

   Спасибо:)) Моя ошибка в том, что все таки недостаточная детализация… Про насыщенность, ты прав, получаются жуткие вещи… Буду пробовать…

macroart.ru

Re-size with HTML

Specify the width and height in your IMG SRC HTML tag as shown in the example below.

<img src="https://www.computerhope.com/cdn/computer-hope.jpg" width="200" height="40" alt="Computer Hope">

How the image appears normally

Using the above code to resize the image

Note: When re-sizing an image, you need to maintain the aspect ratio. Otherwise, the image could become distorted and lose some image quality.

Re-size with CSS

You can also re-size an image through CSS, as shown in the examples below.

img.resize {  width:200px;  height:40px; }

img.resize {  max-width:50%;  max-height:50%; }

In the first example, the actual size in pixels is specified for width and height. Using this option limits the images that can use that CSS. Since it specifies a width and height, this method could result in distorted images if an image does not have a 5:1 aspect ratio.

The second example specifies a percentage of original image size, both width and height, instead of size in pixels. Using this option allows for use with a greater range of images. Since a percentage of image width and height is specified, the browser can resize nearly any image and maintain its aspect ratio.

To apply the CSS to an IMG SRC HTML tag, you would do the following.

<img class="resize" src="https://www.computerhope.com/cdn/computer-hope.jpg"  alt="Computer Hope logo small">

Using CSS results in shorter IMG SRC tags, as the width and height is handled with CSS and you only have to specify the class name in the tag to activate the CSS code for that image.

www.computerhope.com