How to improve the quality of a JPEG image

How to improve the quality of a JPEG image
How to improve the quality of a JPEG image
Anonim

The JPEG (or JPG) format is one of the many formats for image files. It has the advantage of giving images that are relatively small in weight in bytes and of good quality. This format is very convenient for transferring files. However, enlarging a JPEG file gives poor results, the image is not sharp, but thanks to some photo editors, online or in app, it is possible to fix things by playing on the sharpness, the contrast, color… Photoshop is certainly the best photo editor on the market, but it is quite expensive. On the other hand, online, it is possible with the Pixlr site to do good retouching. It is free, but for more advanced features, you will have to get your hands on the wallet.

Steps

Method 1 of 2: With Pixlr

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Step 1. On your browser, go to Pixlr

It is a powerful online photo editor, widely used by professionals and amateurs alike. Pixlr is both a free and a paid site in case you want better features. There are two subscriptions, one at 4.9 € / month and the other at 14.99 €).

Pixlr E can handle images up to a resolution of 3,840 x 2,160. If you wanted to process larger photos, you would have to go through other more professional editing software, such as Adobe Photoshop

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Step 2. Click LAUNCH PIXLR E

At the bottom of the page, click on the right option (Pixlr E). Of the two available versions of Pixlr, this is the more interesting for the work we are interested in here.

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Step 3. Open the image to edit

The quality of a retouched image largely depends on the quality of the original image. Pixlr advises its users to always start with the highest resolution image possible. Indeed, working on a low resolution image is always possible, but, to take just one example, the enlargement of such an image will cause its distortion, the white spaces (due to the voids created) between the pixels will be more and more visible. To upload an image to the Pixlr server, proceed as follows:

  • click on OPEN IMAGE, a green button in full page;
  • navigate in the tree structure of your hard drive to find the affected image;
  • click once on the file concerned;
  • click on To open (Windows) or To choose (macOS).
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Step 4. Optionally resize the image

The size of an image is defined by its number of pixels in height and width. The higher these values, the greater the weight and the longer it takes to upload or download the image. That’s why, if possible and relevant, sometimes you need to resize your original image so that it is easier to manipulate. Note: If increasing the size of an image does not improve its quality, decreasing it can lead to a loss of quality. To resize an image in Pixlr, do the following:

  • click in the left column on the second icon (LAYOUT AND TEMPLATES);
  • left click on IMAGE RESIZE;
  • move the cursor to the right Limit proportions;
  • change the dimensions Width and Height at the top of the window;
  • click on APPLY.
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Step 5. Crop the image

Cropping (or cropping) allows you to keep an image only what is useful in order to further lighten the weight of the image. In the left column of features, the crop (6e element) has two overlapping right angles as an icon. The exact name of this feature is CROP & PIVOT. To crop an image, proceed as follows:

  • left click on CROP & PIVOT;
  • bring the mouse cursor over the outline of the image, it turns into an arrow, then move this arrow in such and such a direction;
  • click at the bottom left on APPLY when you are satisfied with the result.
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Step 6. Use the Clarity filter

Depending on your setting, this filter can enhance details or, on the contrary, reduce them. To adjust the clarity of an image, do the following:

  • click up on the menu Filtered (7e menu);
  • hover over the submenu Details (3e heading);
  • click on Clarity;
  • move the potentiometer to the right (more details) or to the left (less details);
  • click on APPLY.
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Step 7. Play with the Sharpness and Blur filters

If the result obtained with the tool Clarity was not enough, you can still use 2 other filters with a somewhat similar role: filters Sharpness and Vague, their names meaning what they mean. For this adjustment of the sharpness of the image, here is how to operate.

  • Click on the menu at the top Filtered (7e menu).
  • Mouse over the submenu Details (3e heading).
  • Click on Sharpness Where Vague.
  • Move each of the faders to the right or to the left.
  • Click on APPLY.
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Step 8. Reduce image noise

In a digital photo, noise is a parasitic fluctuation that leaves a trace on the photo. To eliminate this noise, this interference, operate as follows.

  • Click on the menu at the top Filtered (7e menu).
  • Mouse over the submenu Details (3e heading).
  • Click on Remove noise.
  • Move the faders to the right or to the left, together or separately:

    • Ray: Adjusts the extent of detail to which noise cancellation is applied;
    • Threshold: Sets the degree of difference that results in noise cancellation where it is applied.
  • Click on APPLY.
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Step 9. Touch up details with the Clone tool

This tool's icon is the profile of an ink pad. The principle is simple: you have an area of ​​the image that does not have the right texture and you make it look like another area. Activate the brush, draw a pattern on the area that has the correct color or texture, then click on the areas to be corrected. This tool is also used to make elements disappear under a pattern that you do not want. For this pattern duplication, proceed as follows:

  • click on Clone in the left toolbar;
  • click above on Brush on the second line of the screen;
  • make all the settings you want (brush size and shape, effect, step, etc.);
  • click on the green button Source on the second line of the screen;
  • click on the area that will serve as a sample for other areas;
  • click on the areas to modify with the color of the sample;
  • repeat the operation as many times as there are zones to modify.
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Step 10. Refine your image with other tools

Pixlr provides you with a number of specialized tools to edit locally or generally the image. These tools are in the left toolbar. So, to use the brush, you click on its icon (second column of tools), then at the top, select the size, effect and step, but also the shape of the brush. Instead, try the soft effect ! There are other tools.

  • Blur / Emphasize / Spread: its icon is a white drop. Click on this tool in the left toolbar, then on the second line of the screen (Fashion), make your settings which are three in number:

    • SHARPNESS: with this tool, you will make the outlines sharper;
    • VAGUE: with this tool, you will blur the outlines;
    • SMUDGE: this tool homogenizes the pixels.
  • Sponge / Color: its icon is a kind of sun. Click on this tool in the left toolbar. On the right of Fashion, select TO AUGMENT Where DECREASE to increase or decrease the effect. On the same line, modify certain color settings with the item Method. You have three options:

    • VIBRANCE: this setting allows you to increase or decrease the intensity of the colors;
    • SATURATION: this setting increases or decreases the color saturation;
    • TEMPERATURE: if you increase it, you get a more orange or red rendering, if you decrease it, you will have a rendering in shades of blue or purple.
  • Color density - / +: its icon is a half-white circle. Click on this tool in the left toolbar. With the mode LIGHTEN, you can brighten an area by clicking on it. With the mode OBSCURE, you will drive it. To qualify these two modes, select, at the top right of the section Range one of the three possibilities, namely DARK TONES, HALF-TONE Where LIGHT TONES.
  • Correct / Repair: its icon is a schematized dressing. This tool allows with the method PATCH Where FILLING to make targeted corrections.
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Step 11. Work on color and contrast

Thanks to some of its tools, Pixlr will allow you to rework the colors of your image, in particular the contrast, the brightness, the tints and the saturation. Playing with contrasts makes light and dark colors stand out, the brightness affects the whole image (it is either lighter or darker), with the change of hues you drastically change the colors and saturation changes the intensity colours. Here is how, for all these settings, you must proceed as follows:

  • click on the top menu Adjustment;
  • click on Contrast & brightness Where Hue & saturation;
  • play on the various potentiometers to make your adjustments (brightness, contrast, hue, saturation and lightness);
  • click on APPLY when you are satisfied with the result.
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Step 12. Save the image

Once the image has been modified to your liking, all that remains is to save it. The compression rate of high resolution images is lower, the image weight remains high, the saved quality is better. The reverse, for low resolution images, is also true: higher compression, lower quality, because more pixelation. To save an image, proceed as follows:

  • click on File;
  • click on To safeguard;
  • in the field File name, type the name of the image you want;
  • click on DOWNLOAD.

Method 2 of 2: Using Adobe Photoshop

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Step 1. Run Photoshop

The Photoshop icon is shades of blue, the two letters "Ps" are common to all versions. This software can be used after taking out a subscription (there are several depending on your profile) of approximately 24 € / month. Click here to subscribe.

Photoshop can do everything, but if you only wanted images to put in your Facebook or Instagram account, it would be pointless, social networks do not allow the enhancement of quality: use Pixlr instead, you will have correct images, not too cumbersome to upload and you won't have to invest in paid software

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Step 2. Open the image to edit in Photoshop

It's very simple, the procedure, as with many other software, is as follows:

  • click on File;
  • click on To open;
  • click once on the relevant image file;
  • click on To open (PC) or To choose (Mac).
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Step 3. Make a copy of the image

With Photoshop, as with any image retouching editor, it's good to make a copy of the original image in case you go wrong during retouching. To save a copy of the original, proceed as follows, the image is already open in Photoshop:

  • click on File;
  • click on Save as;
  • in the field File name, type a meaningful name for your new image;
  • select below (field Format) the file format (JPEG, GIF, PNG, PSD);
  • click on Save.
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Step 4. Optionally resize the image

The size of an image is defined by its number of pixels in height and width. The higher its values, the greater the size (in bytes) of the image. An image made up of millions of pixels takes a long time to send (email, upload) or download. That’s why, if possible and relevant, sometimes you need to resize your original image so that it is easier to manipulate. Note: If increasing the size of an image does not improve its quality, decreasing it can lead to a loss of quality. For resizing in Photoshop, follow these steps:

  • click on Picture;
  • click on Image size;
  • type the desired size in the 2 top frames: Width and Height;
  • click on OK.
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Step 5. Crop the image

This operation allows you to remove any parts of the original image that you feel are irrelevant. By doing this, the size in bytes of the new image is smaller. The tool Crop icon at the top of the left toolbar is two right angles that overlap to form a square. To crop an image, do the following:

  • click on the icon Crop in the left toolbar;
  • click in the upper left corner of the future dimension and drag the mouse to outline your image;
  • to change the crop slightly, click in the corners and drag the image;
  • to finish, validate the operation by pressing the Enter key.
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Step 6. Locate the Noise Reduction filter

It is in a sub-menu of the menu Filtered. It is used to improve luminance and chrominance noise. To activate this filter, the procedure is as follows:

  • click on Filtered;
  • click on Noise;
  • click on Noise reduction.
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Step 7. Adjust the various noise reduction settings

To get started, check the box Overview in the left part of the filter window. Thus, you will be able to immediately see the changes you make by your settings. These are done using sliders that are moved to the right and left. There are three possible settings.

  • Intensity: with this slider, which you will move in the direction that suits you, you will be able to choose a degree of noise suppression. The value will need to be increased for a low resolution JPEG image.
  • Keep details: Setting it to a low percentage will give you a smoother image with smoother edges, the advantage is that you will reduce noise a lot.
  • Emphasize details: To compensate for a low percentage retention of details, you can with this setting, restore sharper outlines. Play around with the 2 settings to get what you want.
  • Check the bottom box Delete the JPEG artifact. This option removes what is called the "mosquito net effect", a blur that results from the movement of the thing being photographed or flaws that appear as a result of compressing a JPEG image.
  • If you are satisfied with the preview, click on OK to save the new image.
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Step 8. Use the Blur or Sharpness filters, but in an optimized version

Depending on the case, you will need to use either of these filters. The first will be to soften the outlines, while the second will allow you to highlight the details and outlines. For these 2 filters, here is how to do it.

  • Click on the menu Filtered in the top menu bar.
  • Hover with the mouse cursor Vague Where Reinforcement.
  • Click on Optimized blur Where Optimized sharpness.
  • Check the box Overview to immediately get an idea of ​​the transformation.
  • To modify the blur or the sharpness, play on the adjustment sliders of the chosen filter, there are two of them:

    • Ray: you will be able to specify the radius of the perimeter in which the filter must search for dissimilar pixels to attenuate or exacerbate;
    • Threshold / Gain: This allows you to define the degree of difference causing the elimination of pixel values ​​and the quality of blur or sharpness.
  • Click on OK.
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Step 9. Make the mosquito net effect and isolated pixels disappear

If in your image there are large areas of solid color, it may happen that when zooming in isolated pixels of another color or along the dominant parts, a sort of cloud of unsightly pixels (mosquito net effect)). Thanks to a sampling of the dominant color, you will be able to make these unwelcome pixels disappear. To deal with these two problems, there is only one solution:

  • to enlarge the area to be reworked, press Control ++ (Windows) or

    Control ++ (macOS);

  • to select the tool Pipette, click on the dropper icon in the left toolbar;
  • click with this tool on the color that will serve as a sample for another area;
  • to select the tool Brush, click on the … brush icon in the left toolbar;
  • click on the white circular icon at the top of the option bar to open the settings panel;
  • set the brush hardness to 10% and above, the opacity to 40% and the flux to 100%;
  • Press on !

    and :

    to change the size of the brush;

  • the color is done by placing the brush in the place to be treated: there, click once.
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Step 10. Use the Clone Stamp tool in some cases

Working through pixels one by one and changing color at each pixel is tedious, sometimes impossible: that's what the Clone Stamp tool is for. This tool allows in a given area to take a pattern (multiple colors) and use it to homogenize the area in question by removing retouching, badly erased pixels, etc. To select and configure this tool, operate as follows:

  • click on the icon which represents a real rubber stamp in the left toolbar;
  • click on the white circular icon at the top of the option bar to open the settings panel;
  • set the hardness to a maximum of 50%;
  • set the opacity to 100%;
  • Press on !

    and :

    to change the size of the brush;

  • hold down the alt = "Image" (Windows) or ⌥ Option (macOS) key, then click near the area to correct, where the desired pattern is located;
  • click once on the area to be corrected;
  • repeat the operation as many times as necessary to obtain the desired result. Of course, if you change the area, you will change the texture.
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Step 11. Refine your image

There are a lot of tools in Photoshop that can greatly enhance an image, and it's not always easy to use. Some of them allow action on part of the photo, while others affect the entire image. The tools are grouped by major functions. Each is symbolized by a general icon on which you only need to make a long click to display the different tools in the section: all you have to do then is select the desired tool. Click on the circular icon at the top of the option bar, then select a brush shape and size. Clicking on !

and :, you change the brush size. For a beautiful rendering, use a brush in the shape of a circle with a muted edge.

  • Sharpness: the icon is a triangle. This tool makes blurry areas sharper. Sharpness is under the same heading as the Water Drop and Finger tools.
  • Water drop: his icon is … a drop of water! It will allow you to blur the pixels and therefore the outlines of an image. The Water Drop tool is in the same section as the Sharpen and Finger tools.
  • Finger: the icon represents a dotted index. This tool allows data to be spread over an image. The Smudge tool is in the same section as the Waterdrop and Sharpen tools.
  • Sponge: its icon is a small circular sponge. This tool allows you to change the color saturation of an area of ​​the image. The Sponge tool is in the same section as the Density - and Density + tools.
  • Density -: the icon is a syringe bulb. This tool helps brighten certain parts of the image. The Density tool - is in the same section as the Sponge and Density + tools.
  • Density +: the icon is a flicking hand. This tool will allow you to obscure certain parts of the image. The Density + tool is in the same section as the Sponge and Density - tools.
  • Correction tool: the icon is a kind of bandage. As the name suggests, it is used for touch-ups locally. This tool is in the same section as the Red Eye tool.
  • Red eye: the icon is an … eye! As its name suggests, it is used to make classic red eyes disappear from a photo. Click and drag a box around the eye to be rectified. The Red Eye tool is in the same section as the Healing Tool tool.
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Step 12. Make various adjustments to fine-tune the colors and brightness

Photoshop provides you with varied and very fine adjustments. Playing with contrasts makes light and dark colors stand out, the brightness affects the whole image (it is either lighter or darker), with the change of hues you drastically change the colors and saturation changes the intensity colours. To change your image, you can do the following:

  • click on Picture;
  • click on Settings;
  • click on Brightness / Contrast Where Hue / Saturation;
  • adjust the various knobs to obtain the desired brightness, contrast, hue and saturation;
  • click on OK when you are satisfied with the result.
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Step 13. Save the image

Once your image has been modified according to your wishes, all you have to do is save it by doing the following:

  • click on File;
  • click on Save as;
  • in the field File name, type a meaningful name for your new image;
  • select below (field Format) the file format (JPEG, GIF, PNG, PSD);
  • click on Save.

Advice

  • With experience, you will know how to use Photoshop tools perfectly. However, there are many and not everyone is well versed in the art of processing images, the vocabulary is not always explicit. Make changes, test tools, and if that doesn't suit you, you always have the option of undoing what you've done.
  • By default, Photoshop only keeps the last 20 actions in the History palette. However, retouching photos requires many actions, small certainly, but many! These 20 actions are therefore not enough for a big retouching job. To increase this value, go to Editing, then Preferences, then Performance. In the window, locate Historical states, click the right triangle, and then move the slider to a higher value.
  • If your file is a high resolution photo, as a newbie to editing, what you think is a blue flower, one solid color, is actually a flower with lots of different colored pixels. The same goes for shadows which are made up of dozens of pixels of different colors. To rectify such areas of color, you have to work pixel by pixel (that's a long time!) Or use the duplication buffer while taking a sample.

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